In a move that I'm sure doesn't involve any patent violations *cough*, Chinese photo gear manufacturer Yongnuo is planning to release a EF mount 100mm f/2 lens that looks strikingly similar to Canon's EF 100mm f/2 USM.
We're uncertain just how Yongnuo traverses this slipperly slope, but... it wouldn't be the first time. Maybe since the focus distance scale turns in the opposite direction as the focus ring, Yongnuo can claim a completely different design?
Update: Ah, it looks like the EF 100mm f/2 USM was designed and patented long enough ago that the patent has run out.