If you load a clip into the Final Cut Pro 5.0 viewer, modify it to a be a subclip, and then send it to the Waveform Editor in Soundtrack Pro 1.0, you may notice that the subclip plays the wrong part of the audio file. You'll hear audio from the In point of the the original clip—not the new In point of the modified subclip. (This only occurs when you send a subclip to the Waveform Editor, not when you send it to a Multitrack Project.)
This article will be updated as more information becomes available.