Also at Tech-Ed, we had some awesome hands-on labs using a post-beta1 build of the product (side note: I really enjoyed the healthy competition between the exchange labs and the other products... the proctors of our labs (and me!) were really proud of how many people we had do our labs as compared to others :-).
We gave away DVDs with the virtual PC images of the hands-on labs to attendees at tech-ed, but we still have a ton of those DVDs left over. This is not a full installable build, and it's not beta 2, but it is an interim build of the hands-on labs in a VPC image that you can play around with until beta2 is available.
The build is called "DF4" internally, short for Dogfood 4, the fourth major fork of a build we've put in our dogfood environment since beta1 - we've since moved on to later builds in production for the 6000 folks we have dogfooding e2k7 at microsoft, it takes a long time to get labs and images prepared.
If you weren't at tech-ed and would like to receive one of these DVDs, I put my hands on a bunch of extra ones. Please send a pre-addressed stamped envelope that is at least 6" x 8" to us inside another envelope. Include enough postage to get the DVD back to your address, wherever in the world you are - the DVD package is a couple of DVDs inside some cardboard, it's only a few ounces.
Any envelopes sent to us that are not fully addressed, don't have the right postage, aren't big enough, etc will not be returned and we will not contact you to notify you of this - sorry, but I'm expecting to get a lot of requests, and I just don't have the time to micromanage at that level of detail.
Send it to:
Tech-Ed VPC DVD
One Microsoft Way
Redmond, WA 98052
And if you want, include a note in the envelope that has an explanation of your favorite feature(s) in Exchange 2007, we'd love to see those :-)