I don't think there is a current SO question addressing this; but if there is please point me to it and I'll close this one.
Anyways, suppose html like this:
<div>
  <div class="a" style="float:left;"></div>
  <div class="b" style="float:left;"></div>
  <div class="c" style="float:left;"></div>
  <div style="clear:both;"></div>
</div>
Is there any css rules I can define which alter the styles of the OTHER elements when hovering. So, something like
  .a:hover {
     // change bg colors of .b and .c
  }
I know I can do this with hover events in javascript; but I was hoping for a css only solution. If you can point to some part of the css spec that says this is NOT possible then I will still mark that as an answer. (Even though I'll admit I didn't read the whole thing; I did read some of it).
EDIT: The answers everyone marked seemm to work and are the correct answer; but they don't work in Chrome/Safari (but IE8 is fine...go figure :P). See here: Why doesn't this CSS selector work: a:hover ~ span?
 
     
     
     
    