For anyone who has used iSightCapture and has been frustrated by the fact that it's released in object-code only format, here is qt-capture which is not quite as capable as iSightCapture (it doesn't have any command-line arguments) but does basically the same thing. Since it's just a proof-of-concept and not really finished code I've released it into the public domain. Enjoy.
UPDATE: I've also uploaded an expanded version that lets you capture movies and still images. It also demonstrates how to roll your own cocoa app without using a NIB file. Not really recommended, but kinda cool to see how it's done for someone like me who really like to know what's going on under the hood.