Cell is being used - but but not to it's full potential STI (Sony Toshiba IBM )are continually developing new software models and cell accellerated libraries etc for cell so newer games will be better.
As for 1080p games cell can help the GPU but is better for other things like advanced interactivity ie PS3 eye face or image recognition, Voice recognition, Physics , Real AI with neural networks (not the scripted crap you get currently) and other features. Though dont expect to see this sort of stuff for a while as it seems beyond the understanding of most current developers.
The Cell of course is based on the original T1000's CPU which had 64 SPU's and 4PPC's - sadly the AI software was unable to be recovered however(perhaps fortunatly) 
PS3 number 1 fan
