As various publications are already reporting, BioWare's Dragon Age II has been pulled from Steam. Considered the timing, which pretty much coincides with the release of its first story-based DLC, Dragon Age II: Legacy, it's easy to suspect that the game is in a situation similar to that of Crysis 2 (another EA game), which, according to Electronic Arts, had been pulled by Valve due to EA's choice to not sell its DLC on Steam. It should be noted that this is just speculation at this point and that other games in Steam's catalog, like Dirt 3, don't offer their DLC on Steam but haven't been pulled from Valve's service.