My GTA froze up as well, multiple restarts and it wouldn't get passed the loading screen (even after a 15 minute wait). Mine happened at first during gameplay while roaming the city, then after that during a cutscene and then the stuck at loading screen began.
I'm pretty disappointed by this, okay we know there was an incident with CoD4 a while back, but it was never proven that CoD4 was the issue with the broken PS3's (chances were it was a coincidence and a demonstration of the lack of PS3 games back then), in this case it is GTA's fault for sure (I feared the worst and tried the 3 other games I own and all of them worked perfectly).
I guess it's what happens when you believe the hype...
EDIT: I should say, issue seemed to be fix for me. I deleted the install file (under game data utility) and the saved files, it didn't work the first time, nor the second but 3rd times the charm.
