There is a new version of the API available on
http://stage.gdata.youtube.com
It will be running at that URL for approximately one week before it
is pushed to the production URL. The new API version contains a number
of new features--we'll go into more detail about them once they're
live in production. While we don't anticipate there being any
incompatibilities with the current feature set, as a best practice we
do encourage developers to test their code against the staging server
and report any issues at
http://groups.google.com/group/youtube-api-gdata
Cheers,
-Jeff Posnick, YouTube API Team