

Those anxiously awaiting Steam for Mac can get started downloading now. The client download link is now live at the following url:
http://store.steampowered.com/public/client/steam.dmg (direct download)
Unfortunately, it appears that the Steam service itself is not ready for users and is still restricting logins to beta participants:

Steam for Mac is supposed to officially launch today so we expect that restriction will be lifted soon.
Article Link: Steam for Mac Client Available for Download, Service Not Yet Active