Well, a few places. Some media outlets, some forums, etc.
Basically, some genius tried to run Netflix on his French PS3, and naturally it's region locked. Somehow this information got reported as "PS3 FW 3.50 NOW HAS REGION LOCKING" which is largely incorrect, since what little region locking there is on the system has been there for AGES.
So yea, basically took no news, blew it up, and made a fuss out of nothing.
The person who noticed it was one of the contributors to ps3 jailbreaking efforts; he knows what he's talking about. It isn't that "PS3 3.50 now has region locking", it's more like "Sony has been implementing region locking since at least FW 3.30, but it hasn't been used yet."
At the moment it's a PARAM.SFO field known as REGION_DENY. It's naive to say the "PS3 isn't region locked." Perhaps "PS3 isn't region locked for now"?
In any case, you can see it in (limited) action on a debug unit here: http://jerem73.wordpress.com/2010/10/21/region-restriction/