There are no rules for BD region-locking, publishers are free to lock or leave region-free. Most major publishers have done both depending on which title. The region code is on BD boxes regardless of whether the disk is region-locked.
Of course if you buy from the region that matches that of your BD player, you don't have to check anything.
http://regionfreemovies.com/ is a useful database, though more so if you are buying US bluray editions.
Or, if you have a specific film in mind (and region where you want to purchase it), google for another list/forum post or something else that might be helpful.
edit: http://regionfreemovies.com/bluray/Samurai_Champloo_-_Complete_Series_%28Collector%2527s_Edition_Box_Set%29 regarding the Samurai Champloo collection. Region-locked, so you'd need either a US or JP BD player/PS3.
