Nope. One of the biggest and most legitimate feature requests.
Here's a pseudo-workaround: Create a piece of Slug, delete the video portion, and put the Slug at the beginning of the audio track. Select it and press APPLE-9 to rename it to whatever you want.
Of course, this still isn't all that great because you can only see it if the beginning of the track is in sight. But maybe it will help a bit.
www.derekmok.com