Yup.
http://www.joystiq.com/2010/04/21/steam-on-mac-video-leaked-looks-like-steam-on-windows/
i have yet to watch the video and all but it's posted on Joystiq!
pretty cool, as you guys know i dont like reading, even if it means getting the steam for mac beta. Please post if there is a link to the application.
Word on the street is that it's coming out monday with the pc ui update. At least that's what the aliens told me....
im gonna physically go beat up Steam for decided to release this UI in LATE April, as opposed to anytime earlier or in tandem with Windows.