[Update - 2:10pm CST] The Steam Mac Games Store is now open, offering over fifty games and various launch day discounts, such as half-off Torchlight--making it $9.99--and 70% off Quantz, which brings that game down to just $3.00.

In addition, Valve's clever shooter-puzzler Portal is free on PC and Mac until May 24.

Watch the HD video on Shackvideo.

As noted below, all of the Steam for Mac launch titles offer a free Mac version to those that already own them on Steam PC thanks to the "Steam Play" feature, "which allows customers to purchase a game once and play it on all Steam supported platforms."

For a full breakdown ...

Read More