According to a forum post on the Steam forum (via Kotaku), 3 million promo keys of DiRT 3 have leaked. The codes, which were given out as part of a promotion between Codemasters and AMD when you bought a graphics card from the latter, were part of a list that found its way online. As the codes belong to Steam, it would be simply a case of blocking any said code that was part of the list from the service to prevent it being played.
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