In case you missed it, check out this report on who is using Twitter. The surprise (to me): it's not teenagers. The biggest group of users is the 25 to 54 years old crowd. Here's a post that may help explain why.
But wait! Here's an alternative view . So maybe teens do tweet! As usual, read all the info and make your own determinations.
And since we're on a report role, check out this Pew Internet Life & American Life report on the audience for online video-sharing sites . 62% more adults visited online video sharing sites in 2009, up from just 33% in 2006.