First off, I'd strongly suggest upgrading to IPython 1.1.0, as while the issue likely isn't related to the older version, it's well worth the upgrade, especially if you use it a lot.
If you open Preferences -> Package Settings -> SublimeREPL -> Settings - Default, you'll notice that the last line is "show_transferred_text": false. I'm on OS X, but when I have this set to false, I see the same behavior you do - the result of the expression printed on an In [#] line, with another blank line following it, ready for the next expression. However, if I set this variable to true (by copying the entire contents of the file, opening Preferences -> Package Settings -> SublimeREPL -> Settings - User, pasting everything in there, then changing settings and saving), then I see different behavior when transferring a line: The expression is printed on the In [#] line, and the result is printed below.
The reason you didn't see any results when evaluating the assignments to x and y is because nothing is returned, by default.
By way of explanation as to why the Python/IPython REPLs work this way, while the R one doesn't, is because SublimeREPL is very modular, and for the most part is just a thin wrapper surrounding native code. Therefore, the exact mechanism of transferring and displaying data may differ from Python to Ruby to R to Clojure, for example, and you may see slightly different behaviors.