Gears of War 2 will allow you to unlock content by earning Achievements in Gears of War 1.
That's according to Cliff Bleszinski, speaking at Comic-Con (thanks Kotaku), who also detailed a few of the "linked Achievements".
According to Bleszinski (and bear in mind that these might be considered spoilers!), if you completed Act One in the first game, you'll unlock a playable Anthony Carmine in the sequel.
If you found ten COG tags, you'll unlock Minh Young Kim, and if you killed General Raam, you'll unlock a playable version of the cuddly old dinosaur in Gears of War 2 as well.
Kotaku notes that Bleszinski didn't clarify whether these will be for single-player or multiplayer, but we'd put our money on the latter.
As you will know if you've been following coverage of Gears of War 2, including our hands-on and interview with Bleszinski from E3, Epic has yet to say whether you'll play as anyone other than Marcus and Dom in the single-player/co-op campaign.
While we're on the subject of Gears at Comic-Con, attendees were also told that Steve Jablonsky is working on the score.
Jablonsky's IMDB page reveals that his past videogame work includes a couple of recent Command & Conquer games, and that on the silver screen he's worked on the Transformers movie and American horror films.