They've pulled the firmware until they can sort it out. I'm running 4.41, and it says I'm on the latest release.
The problem only seems to affect PS3s with user-upgraded hard drives. Specifically, hard drives of 500GB or larger. It's not 100% of the time, so if you might have been okay, but from what I could tell, every failed unit had a non-factory hard drive in it.. there were no reported cases of the firmware causing an issue if you still had the factory hard drive.
It's moot now, since they've pulled it. I'll update when they put it up next, presumably in a couple of days, and go from there. My system's still stock, so I'm not that worried.
I really wanted this one, too.. this is the update where they finally added the ability to turn off Trophy notifications.