When I first started playing Fallout New Vegas on my PS3 I was experiencing system lockup issues very frequently, like every 5-15 minutes. The game was basically unplayable and I was about to give up on it when I tried unplugging my internet cable from the back on my PS3 to see if it helps. It did!! Since I did this I have had zero, none, not one single, lockup for the last 15 hours of play. The game is actually playable now, thank goodness, and its a pretty darn good game. Too early to say if its comparable to FO3, but the longer I play...without constant lockups and frustration...the more I like it.
Just thought I'd pass that along. It may not work for everyone, but if at least one person reads this and it helps then it was worth it.