http://support.apple.com/kb/HT2405

"Includes extensive graphics enhancements."
I wonder what those are, exactly?

hehe, I haven't noticed any differences yet =/

I wanna know if it actually changes anything though, so if anyone finds out...

hmm, well, no noticeable differences . Imac 24 " , 2,8 gig extreme

Yeah, no noticeable differences here either (1st Gen MacBook Pro)

No difference here either. MacBook C2D 2Ghz

I hear those 'graphical fixes' had nothing to do with OGL, but rather with image file type support.

Edit: On a sidenote, since the update, HD .mkv files play much smoother on my MacBook Pro... not that it has direct bearing on this.