So Firefox and Chrome will support WebM natively. Google will release a WebM plugin for IE and Safari. Then we will finally have a universal video format for the web.
The only odd man out is iOS. I don't know if Safari supports plugins on the iPhone and iPad. These guys are already kind of screwed because they didn't supoprt the last "universal" format, Adobe Flash. So nobody should be surprised by "oh, it's an iPhone. Can't play online video."