Just adding my two cents, I've also had my PS3 freeze three times yesterday, and I think one other time since the 2.1 patch. Doing a quick search I found a couple threads on GameFAQs that they've started freezing since the patch.

It's still a small enough sample size that it *could* just be dirty/overheating PS3s, and it's a coincidence that it's been happening since the patch (or the patch is just putting that liiittle extra stress on the console)... or it could be some inherent bugginess in the patch itself causing PS3s to freeze.

For my own part, I think every time I was either in Gridania or zoning out of Gridania.