As promised, Valve have just announced that the debut Mac version of their digital download game platform Steam is now available, alongside a batch of nearly 60 games, including a free download of Valve's own Portal (through May 24th). While the selection of AAA 3D titles is more limited than its Windows counterpart for now, it does include good representation from the adventure game set, like LucasArts and Telltale, and by the indies, including Braid and a discount 5-pack of World of Goo, And Yet It Moves, Galcon Fusion, Osmos and Machinarium. Also, "Steamplay" titles previously bought through the Windows version of the client are automatically activated in your new Mac account -- the company promises more of those every Wednesday through the coming months. Download the client here [.dmg link], and see Valve's Mac section here. Click through for the full list of launch titles.