i know pal master system games can be played in a US master system no prob, but can pal games be played in a us pbc? i wouldnt see why not but then again mebbe they locked out pal games somehow with the genny?
Further to what Arakon said, the US PBC is identical to the European one. It's the Genesis or MD itself which determines whether the system is PAL or NTSC. (I.E. if you plug a European PBC into a US Genesis, the output will be NTSC, not PAL.)
Incidentally almost all SMS games are exactly the same for the US and Europe, apart from the packaging and labelling. Only a few exist in separate "PAL" and "NTSC" versions - Galaxy Force and Space Harrier are two examples.