[Tim Wilson] "It's worth nothing that Adobe was way, way out in front on this with Acrobat. There's an article in the COW library talking about the uses of this for video (marking up frames, adding notes and the like) something like 6 years ago."
Yes, Adobe Clip Notes. It was in the CS4 Suite for Premiere Pro and AE. It was a useful function... I'm not sure why Adobe killed it.
http://library.creativecow.net/articles/rabinowitz_aharon/Clip_Notes_1.php
Shawn