I'm a fan of Eyejot, one of several online products that makes it very easy to send a video message. Eyejot uses Flash and your Webcam to skip the annoying video upload stage: you just just look at your camera, press record, and you're making a video. Eyejot messages come as e-mails with links to the recordings. Today the company extends on that model with a new Eyejot This feature that will, optionally, send a message to your Twitter account.
Eyejot This is really designed to let you create video commentaries on Web pages, and it's accessed by a bookmarklet you install in your browser. When you click on it and record video, the result is a link to the Web page you were on when you clicked it, with your small video in a frame above the page. Here's an example.
You can also use Eyejot This to send your recordings by e-mail, but e-mail recipients don't get the same cool video-on-Web-page format that Twitter readers get.
See also: Twiddeo, a mashup of V.Social and Twitter that works from a mobile phone (cool) but not from a Webcam (boo), and Seesmic, a soon-to-be-released video utility that will also create Twitter messages.