I should probably point out that with each release of Lightroom, Adobe has added more editing features and improvements. Their goal seems to be to get most photographers away from Photoshop and into just Lightroom. ACR has amazing power so a lot of the editing I used to do in Elements is now done in ACR of CS5. Since the same engine is in Lightroom, the editing could be done there instead.
I use CS5 for printing multiple images onto a single page with a lot of text with specific layout, very accurate lens correction, a layers exercise that processes a raw photo multiple times and combines the result — like HDR, focus stacking, creating moving GIF files, and blurring or changing backgrounds that have complex masking challenges. Most of the rest has been taken over by ACR.