Game company Valve has announced today that it’s finally bringing over its Steam digital distribution platform to Macs.

Steam has long been a very popular platform among PC gamers. It offers a one-stop shop for purchasing and playing games — much like iTunes does for music and media. The service currently offers over 1,000 games and boasts 25 million registered accounts. In 2009, the platform gained 25 percent in new users and saw sales increase 205 percent.

Valve plans to launch Steam on Macs in April, along with all of the company’s games running on the Source game engine — including Left 4 Dead 2, Portal, and Team Fortress 2. Valve has updated Source to perform natively on the Mac, so games should perform just as well as they do on Windows PCs.

Portal 2 will be the first game released simultaneously across both Mac and PC platforms. That alone is significant, since Mac versions of popular PC games traditionally come out several months (and sometimes years) after the PC version. By bringing Steam over to Macs, Valve could potentially help solve that problem.

The company has also announced two new features for Steam that will affect both Mac and PC users. “Steam Play” allows games purchased via Steam on PCs to be available on the Mac, and vice versa. It also means that games Steam users already own on the PC side will be available on their Macs. Even more intriguing is “Steam Cloud”, which will allow players to continue their progress on games across platforms. You could play through a level of Half Life 2 on your PC desktop, and continue at a later point on your Mac laptop.

Valve has taken its sweet time recognizing the Mac as a legitimate gaming platform, but the addition of these progressive cross-platform features will likely make gamers forget about the snub.