Joost clone runs in a web browser
Of course, he doesn't have permission from Joost to use their graphics. Nor does he have access to Joo'st video content. But he's done a pretty good job of replicating the Joost interface using web video from sites like YouTube, MySpace, and iFilm.
The interface isn't perfect. For example you can't use your keyboard to navigate the menus, you'll need a mouse. Given that an independent developer was able to put this together in less than a month, it'd be nice to see Joost come out with something similar. Because while the idea of a standalone full screen video player is nice, the truth is people do spend a lot of time sitting in front of a computer with a web browser open. It'd be nice to give them a better way to slack off at the office.