Looks pretty cool and has received some great reviews. I have a buddy high up the food chain @ Microsoft who says availability won’t be until October.
Sounds about right. Apparently, it will only be available in the physical Microsoft stores or online:
http://www.microsoftstore.com/store/msstore/en_US/home
It would seem Microsoft doesn't want to upset their PC partners too much by offering the Surface Tablet for sale in normal retail outlets.