Just put "-clientbeta betaui" in the target line of a steam shortcut. It'll update and then you can see the beauty!
http://img196.imageshack.us/img196/2117/steambeta27dr.jpg
(Not my screenshot/desktop. Grabbed from someone else.)
http://img196.imageshack.us/img196/2117/steambeta27dr.jpg
(Not my screenshot/desktop. Grabbed from someone else.)