Like previous releases, Microsoft is opening up testing for the new dashboard update. It will let you try out ESPN, the Netflix update, and more. The link to the program is here and more details are on Major Nelson's blog here.
 
You'll need your console handy because the serial number and console ID are required. One or both may be available on xbox.com if your console is registered to your GT, but I'm not 100% sure.  edit: I added instructions a few posts below for finding your SN and CID on the web.
 
After filling out the form I was immediately told that I was in the program, so I guess it fills up when they get a certain number of entries, so act fast.

Anyone know where to find your console serial number/ID on xbox.com?  I'm at work and really want espn3 support!  I found the ID, but not the serial number ... guess I have to wait until I get home and it's full :/

Cool, thanks.  I'll have to check it out.

" Anyone know where to find your console serial number/ID on xbox.com?  I'm at work and really want espn3 support!  I found the ID, but not the serial number ... guess I have to wait until I get home and it's full :/ "

The webpage is broken for me. I guess me being outside the US has something to do with that?

" The webpage is broken for me. I guess me being outside the US has something to do with that? "

" The webpage is broken for me. I guess me being outside the US has something to do with that? "

Okay, got it working. Not sure how I like not being able to be in a party with non-participants. I mean, I just got Reach and all..

 3. Do you understand that Party Chat will not work with people outside of the Preview Program? *   

Got in through the Major Nelson link. Very cool, thank you!

Thanks for the help -- I got in!  ESPN3 is a huge deal for me as I don't get cable and it's not perfectly smooth on my htpc.

Quick question about this.  Me and my girlfriend share a 360.  If we both sign up and one of us gets in and the other doesn't would the one that didn't get in still be able to connect to live, or would they just not be able to access the new features, but still have internet connectivity?
 
Thanks in advance.