Epic Software has recently updated its Unreal Development Kit--which you can totally download and play with if you're a fan of code, the color brown, and Unreal Engine 3--with fresh and sexy Steamworks functionality and a bunch of other gobbledygook that this cornfield-raised Indiana boy plain don't understand.
According to the update notes, the UDK will recognize and now work with Steam's matchmaking, server browsing, and friends junk. Steam is also now the "default OnlineSubsystem for UDKGame Win32." Epic also notes that "Point Lights" are now supported, as well as Scaleform GFx, and some sort of fog business.
If you've got a hankering to learn more in regards to what was added, head on over to Shacknews. If you don't necessarily care--and I get you, brother--just sit back and consider the following: indie and big devs using the UDK will now be able to toss their games onto Steam with the support of most of its systems without much hassle. That's pretty cool, right?