A similar thing happened with Jade Empire. It didnt support surround sound on release either (not sure if it has since been fixed). It's a shame because both the Jade Empire and Gears of War ports would have been near flawless if the sound was properly implemented. It's a pretty major thing for the devs to omit.
In this case, it's clearly there, but because they skimped on the options screens there's no easy way to implement it. I'm not suggesting they go back to Unreal 1 with the crazy outside console with a zillion options, but a configuration like the one in UT2003, Quake 4, HL:2, etc. would be nice. I'm going to guess that UT3's going to be troublesome to configure, too. Seems like that's an Unreal Engine 3 trademark. The GUI looks pretty, but functionality suffers.