Forum

“We recieved a bunch of positive responses to the release of the .vmf source behind our official TF2 maps. As a result, we’ve decided to go ahead and release the source behind all the player character models, as well as associated animations. We hope this will make it much easier for custom modellers to design new character models, and for machinima makers to have more control over how characters animate in their movies. Look for that SDK update in the next week or so.”

http://www.teamfortress.com/post.php?id=2711

Should hopefully encourage more people to do some machinima, and the existing creators to improve their work :>