Valve announced Tuesday that they will be offering free-to-play MMO games via their content delivery service, Steam. The five launch titles available immediately available are Spiral Knights, Forsaken World, Champions Online: Free for All, Global Agenda: Free Agent and Alliance of Valiant Arms. To commemorate the addition to their venue they will be offering exclusive in-game content to players who take advantage of the “Free to Play Game of the Day” on Steam.

The first free-to-play game to be heralded with exclusive in-game content will be Spiral Knights on Wednesday, June 15th, 2011.

“The introduction of Free to Play games is another example of the constant evolution of Steam,” said Jason Holtman, director of business development at Valve. “Free to play games offer new game genres and game experiences for customers while offering developers and publishers new revenue opportunities and the ability to reach customers in areas of the world where the traditional packaged goods model is less popular than F2P.”

According to the literature, in-game microtransactions will be handled by Steam’s back-end system implemented for SteamWorks partners. This may increase the overall profitability of Steam by enabling Steam users to use their financial information stored by Valve to be their go-to place to purchase item store gear for free-to-play games without having to sign up for multiple properties across different systems.

Having already shown themselves as fairly profitable—supporting over 13 million accounts and signing powerhouse publishers like id Software, Eidos Interactive, and Capcom—the inclusion of free-to-play MMO titles on Valve’s Steam will likely promote a greater audience for the genre of games and lend a greater air of legitimacy to the still developing market. The addition of free-to-play games to Steam’s stable puts these titles alongside such high profile games as BioShock, Call of Duty 4: Modern Warfare, and even Duke Nukem Forever.

Already a download-medium, free-to-play MMO properties are perfect for delivery via and publication through Steam. It’s expected that badges generated in games will also be ported into the Steam network and that users will be able to use Steam’s preexisting social messaging service to keep track of what they’re friends are playing and join them in games.

We may be looking at a new era of meta-positioning for free-to-play gaming as a result of this announcement.

[Link, via Steam]