8.1 Alpha2 is available from the download page: http://www.jboss.org/teiid/downloads
Note that the 8.0 download links have been removed as 8.1 to this point is mostly a fix release with over 50 issues addressed. Ideally 8.1 Final will target AS 7.2, but for now it is targeted for use with AS 7.1.1.
We've been getting a good amount of community feedback (thanks to Andriy Rokhmanov, Luca Gioppo, Mark Addleman, Deshi Xiao, Heidi Muehlebach, and others) from 8.0/8.1 and there is still plenty of time to get fixes into 8.1, so keep the issues coming.
The Teiid Team