We're taking the "wait & see" approach to SDMI. As for actual implementation, we don't see any problems - except that the open architecture of the empeg might worry the SDMI people. The SDMI group can exclude any hardware device which they feel doesn't give their music the protection they want: it's a rather, well, silly attitude as SDMI music has to be able to play on a PC, which is about the most open/easily hacked platform there is.
There's nothing in our MP3 decoder which will prevent people from playing watermarked tracks - but then again, noone else's MP3 decoder checks for watermarking yet either.
Legal status? SDMI can't be forced on anyone. They're hoping it'll become the de-facto standard and noone will offer non-SDMI devices. I have a feeling it may not turn out as they'd like...
Hugo