OK, mystery solved. The PS3 firmware update yesterday seemed minor because, well, it was minor. Sony's senior PR manager Patrick Seybold:
...we've released a minor firmware update (version 1.92) for the PS3. This update focuses on some PS3 compatibility and playability issues for select titles. A search site for looking up compatible titles is also in the works.
Since they haven't come out and named them, let's just assume the "select titles" are "Warhawk" and "Lair". Good news on the search site, I guess, since it's been a pain not only finding games on the list but keeping track of any changes. But then that feature should have been there from the start, so we're really just breaking even. Firmware Update (v1.92) [PlayStation Blog]