Google I/O is this week, and this year you can watch the keynote presentations live on YouTube. There will be two streamed events that I know of: one at 9:00 AM Pacific (noon Eastern) tomorrow, and another on Thursday at 8:30 Pacific (11:30 Eastern).
This is a developer event, so I’d expect the content to be geared toward that audience, but if you have just a general interest in Google and the web, you still may find some of the presentations interesting.
To get an idea of what I/O is all about, you can check out last year’s keynotes and sessions on video.