The “About Flash” page reports that the PS3 is running Flash Player 7.0.70.0.
The User-Agent is reported as “Mozilla/5.0 (PLAYSTATION 3; 1.00)”.
For what it’s worth :)
I have not run any Javascript or rendering tests or anything like that. I should see if anyone else has already.
EDIT: Aha! Someone has, and seems to have done quite an exhaustive job of it. Very handy, bookmarking now :)