Um as far as i know BD is region locked too
Yep your right most Movie BRD are marked A, B or C indicating the region the disc is region locked to, however you may (or may not) have noticed that some titles carry no marking, indicating that the are for global use. Indeed some carry a single region label but seem to work none the less on any region PS3. I have several such titles and they work on both my UK and US PS3s. I believe its down to the Studios not having enforced region protection, I guess a bit like Region 0.
Take a look here for a detailed list: http://bluray.lindsite.dk/
As for DVDs and multi-region, no such luck. I have not heard of any codes or unlocks. However as a workaround I simply rip the required DVDs and stream using Twonkymedia. Works great. Alternatively I guess you could also playback the DVD from a PC streaming the output to the PS3 using VLC or similar.