Mac Rumors posted the requirements and some workarounds to view Apple's live keynote stream later today

It came as a surprise to everyone tonight when Apple announced that they would be live streaming video of their September media event across the web. The news, however, was somewhat dulled by the fact that Apple announced that the stream will only be viewable on an OS X 10.6 Mac or an iOS device (iPhone, iPod Touch, iPad). The reason for the limitation isn't entirely arbitrary, as Apple is using a new streaming technology called HTTP Live Streaming which was introduced alongside Snow Leopard's QuickTime X and iOS 3.0.

  Can You Watch Apple's Live Keynote Stream? Requirements and Workarounds