Beta 3 is just on the point of emerging blinking into the sunlight. We have a bunch of Webcasts being run by the US - they're all scheduled for late afternoon/early evening UK time, but you'll be able to watch them after the event. If you keep an eye on www.Microsoft.com/longhorn you'll see when beta 3 is available, and the there is a link to the page with full details of the Webcasts and chats.
Here's a list of what's coming up in May
it seems we're not updating that for the beta 3 release after all. Click the "Register to be notified" link and the page has the download ... sigh.
Update 2: Patience in all things. The Longhorn page was updated a couple of hours after the previous update.