Sony have reportedly said that there is currently "no evidence to indicate firmware 3.61is causing any issues with PS3s" in lieu of Rockstar Games pointing the finger after receiving complaints from users that L.A. Noire was causing PS3s to overheat.
The issue was raised when a number of users playing L.A. Noire had the game and system freeze or randomly shut off by itself after a while, or "Red Lighting," as some would put it. The problem was most noticeable on older 60/80GB fat models.
Rockstar Games have presently put up a Q&A page dedicated to the problem. If you are experiencing any issues, it's best if you check it out.