For the price, build quality, size / weight and awesome image quality, I'll add the following two lenses (which I have) to the list of 'not needing an update'. They are pretty much 'spot on' in my humble opinion, and do not need to have a version II:
Canon EF 70-300mm L USM IS
Canon EF-S 15-85mm USM IS
I like having options (eg smaller lenses - usually not as fast glass - with still very high IQ). The above two are ideal as a two lens travel combination.
Jamesy.... I almost cliked the "Report to moderator" link... about your post of the 50mm f1.4

Ha ha.. I know you were joking!!
That's the one lens I do hope gets an update soon - with true ring type / full time USM focussing, and very good image quality wide open... in fact if it is f1.8 that would also suit me). IS would be a bonus (but not necessary)....

Regards
Paul