Application developers are pretty excited about the technology, and as such we have scheduled a tutorial session about how to make use of the application indicator framework as part of the awesome Ubuntu Developer Week. The session is today, the 26th Jan at 7pm UTC / 11am PST / 2pm EST lead by the always awesome Ted Gould. More info on joining the session is here or you can use Lernid to join really easily.
Recently I have been talking about how stoked I am that we are solving the problems in the notification area with Application Indicators based on this spec from the KDE team. We are now shipping this functionality in Lucid with Rhythmbox, Nautilus, Empathy, XChat-GNOME, Lernid and other applications using it.