Not getting them from playing previous Epic titles
Rumors were touched off some time back that Epic had plans to offer special unlocks for the upcoming Gears of War 3 for those who played Bulletstorm, as well as older Epic titles such as Unreal Tournament 3 and Shadow Complex, that would unlock special items in Gears of War 3.
As it turns out, this is not going to be happening after all, due to a couple of factors. What we hear is that they can’t read the achievements for Bulletstorm, Shadow Complex and UT3 to offer unlocks. It has something to do with Xbox Live data and some potential restrictions around the use of it, or something to that effect.
All isn’t lost, however, as playing previous Gears of War titles will count toward some sort of unlocks; but it is unclear right now what those might be. We do now know that Epic (in conjunction with Microsoft) is planning right now to launch a Gears of War 3 beta sometime around April.