In case it's useful, here's a C++ version of the Java snippet posted by Ribo:
struct decompressXML
{
    // decompressXML -- Parse the 'compressed' binary form of Android XML docs 
    // such as for AndroidManifest.xml in .apk files
    enum
    {
        endDocTag = 0x00100101,
        startTag =  0x00100102,
        endTag =    0x00100103
    };
    decompressXML(const BYTE* xml, int cb) {
    // Compressed XML file/bytes starts with 24x bytes of data,
    // 9 32 bit words in little endian order (LSB first):
    //   0th word is 03 00 08 00
    //   3rd word SEEMS TO BE:  Offset at then of StringTable
    //   4th word is: Number of strings in string table
    // WARNING: Sometime I indiscriminently display or refer to word in 
    //   little endian storage format, or in integer format (ie MSB first).
    int numbStrings = LEW(xml, cb, 4*4);
    // StringIndexTable starts at offset 24x, an array of 32 bit LE offsets
    // of the length/string data in the StringTable.
    int sitOff = 0x24;  // Offset of start of StringIndexTable
    // StringTable, each string is represented with a 16 bit little endian 
    // character count, followed by that number of 16 bit (LE) (Unicode) chars.
    int stOff = sitOff + numbStrings*4;  // StringTable follows StrIndexTable
    // XMLTags, The XML tag tree starts after some unknown content after the
    // StringTable.  There is some unknown data after the StringTable, scan
    // forward from this point to the flag for the start of an XML start tag.
    int xmlTagOff = LEW(xml, cb, 3*4);  // Start from the offset in the 3rd word.
    // Scan forward until we find the bytes: 0x02011000(x00100102 in normal int)
    for (int ii=xmlTagOff; ii<cb-4; ii+=4) {
      if (LEW(xml, cb, ii) == startTag) { 
        xmlTagOff = ii;  break;
      }
    } // end of hack, scanning for start of first start tag
    // XML tags and attributes:
    // Every XML start and end tag consists of 6 32 bit words:
    //   0th word: 02011000 for startTag and 03011000 for endTag 
    //   1st word: a flag?, like 38000000
    //   2nd word: Line of where this tag appeared in the original source file
    //   3rd word: FFFFFFFF ??
    //   4th word: StringIndex of NameSpace name, or FFFFFFFF for default NS
    //   5th word: StringIndex of Element Name
    //   (Note: 01011000 in 0th word means end of XML document, endDocTag)
    // Start tags (not end tags) contain 3 more words:
    //   6th word: 14001400 meaning?? 
    //   7th word: Number of Attributes that follow this tag(follow word 8th)
    //   8th word: 00000000 meaning??
    // Attributes consist of 5 words: 
    //   0th word: StringIndex of Attribute Name's Namespace, or FFFFFFFF
    //   1st word: StringIndex of Attribute Name
    //   2nd word: StringIndex of Attribute Value, or FFFFFFF if ResourceId used
    //   3rd word: Flags?
    //   4th word: str ind of attr value again, or ResourceId of value
    // TMP, dump string table to tr for debugging
    //tr.addSelect("strings", null);
    //for (int ii=0; ii<numbStrings; ii++) {
    //  // Length of string starts at StringTable plus offset in StrIndTable
    //  String str = compXmlString(xml, sitOff, stOff, ii);
    //  tr.add(String.valueOf(ii), str);
    //}
    //tr.parent();
    // Step through the XML tree element tags and attributes
    int off = xmlTagOff;
    int indent = 0;
    int startTagLineNo = -2;
    while (off < cb) {
      int tag0 = LEW(xml, cb, off);
      //int tag1 = LEW(xml, off+1*4);
      int lineNo = LEW(xml, cb, off+2*4);
      //int tag3 = LEW(xml, off+3*4);
      int nameNsSi = LEW(xml, cb, off+4*4);
      int nameSi = LEW(xml, cb, off+5*4);
      if (tag0 == startTag) { // XML START TAG
        int tag6 = LEW(xml, cb, off+6*4);  // Expected to be 14001400
        int numbAttrs = LEW(xml, cb, off+7*4);  // Number of Attributes to follow
        //int tag8 = LEW(xml, off+8*4);  // Expected to be 00000000
        off += 9*4;  // Skip over 6+3 words of startTag data
        std::string name = compXmlString(xml, cb, sitOff, stOff, nameSi);
        //tr.addSelect(name, null);
        startTagLineNo = lineNo;
        // Look for the Attributes
        std::string sb;
        for (int ii=0; ii<numbAttrs; ii++) {
          int attrNameNsSi = LEW(xml, cb, off);  // AttrName Namespace Str Ind, or FFFFFFFF
          int attrNameSi = LEW(xml, cb, off+1*4);  // AttrName String Index
          int attrValueSi = LEW(xml, cb, off+2*4); // AttrValue Str Ind, or FFFFFFFF
          int attrFlags = LEW(xml, cb, off+3*4);  
          int attrResId = LEW(xml, cb, off+4*4);  // AttrValue ResourceId or dup AttrValue StrInd
          off += 5*4;  // Skip over the 5 words of an attribute
          std::string attrName = compXmlString(xml, cb, sitOff, stOff, attrNameSi);
          std::string attrValue = attrValueSi!=-1
            ? compXmlString(xml, cb, sitOff, stOff, attrValueSi)
            : "resourceID 0x"+toHexString(attrResId);
          sb.append(" "+attrName+"=\""+attrValue+"\"");
          //tr.add(attrName, attrValue);
        }
        prtIndent(indent, "<"+name+sb+">");
        indent++;
      } else if (tag0 == endTag) { // XML END TAG
        indent--;
        off += 6*4;  // Skip over 6 words of endTag data
        std::string name = compXmlString(xml, cb, sitOff, stOff, nameSi);
        prtIndent(indent, "</"+name+">  (line "+toIntString(startTagLineNo)+"-"+toIntString(lineNo)+")");
        //tr.parent();  // Step back up the NobTree
      } else if (tag0 == endDocTag) {  // END OF XML DOC TAG
        break;
      } else {
        prt("  Unrecognized tag code '"+toHexString(tag0)
          +"' at offset "+toIntString(off));
        break;
      }
    } // end of while loop scanning tags and attributes of XML tree
    prt("    end at offset "+off);
    } // end of decompressXML
    std::string compXmlString(const BYTE* xml, int cb, int sitOff, int stOff, int strInd) {
      if (strInd < 0) return std::string("");
      int strOff = stOff + LEW(xml, cb, sitOff+strInd*4);
      return compXmlStringAt(xml, cb, strOff);
    }
    void prt(std::string str)
    {
        printf("%s", str.c_str());
    }
    void prtIndent(int indent, std::string str) {
        char spaces[46];
        memset(spaces, ' ', sizeof(spaces));
        spaces[min(indent*2,  sizeof(spaces) - 1)] = 0;
        prt(spaces);
        prt(str);
        prt("\n");
    }
    // compXmlStringAt -- Return the string stored in StringTable format at
    // offset strOff.  This offset points to the 16 bit string length, which 
    // is followed by that number of 16 bit (Unicode) chars.
    std::string compXmlStringAt(const BYTE* arr, int cb, int strOff) {
        if (cb < strOff + 2) return std::string("");
      int strLen = arr[strOff+1]<<8&0xff00 | arr[strOff]&0xff;
      char* chars = new char[strLen + 1];
      chars[strLen] = 0;
      for (int ii=0; ii<strLen; ii++) {
          if (cb < strOff + 2 + ii * 2)
          {
              chars[ii] = 0;
              break;
          }
        chars[ii] = arr[strOff+2+ii*2];
      }
      std::string str(chars);
      free(chars);
      return str;
    } // end of compXmlStringAt
    // LEW -- Return value of a Little Endian 32 bit word from the byte array
    //   at offset off.
    int LEW(const BYTE* arr, int cb, int off) {
      return (cb > off + 3) ? ( arr[off+3]<<24&0xff000000 | arr[off+2]<<16&0xff0000
          | arr[off+1]<<8&0xff00 | arr[off]&0xFF ) : 0;
    } // end of LEW
    std::string toHexString(DWORD attrResId)
    {
        char ch[20];
        sprintf_s(ch, 20, "%lx", attrResId);
        return std::string(ch);
    }
    std::string toIntString(int i)
    {
        char ch[20];
        sprintf_s(ch, 20, "%ld", i);
        return std::string(ch);
    }
};