Sony's Vita is Definitely, Sensibly, Brilliantly Region Free

Region locking generally was originally used to prevent issues with incompatible TV sets, hence why handhelds were never region locked.

That became un-necessary as more modern sets happily accept any signal, but now Nintendo region lock (particularly the handhelds) because of parental controls. With each region having different ratings (and in Europe there are multiple standards) it's more simple just to lock the region of games rather than work out what an ESRB rating would translate to in PEGI, BBFC, USK or OFLC.