G4TV have released a bunch of clips from Reach's multiplayer modes
First here is a full match of Firefight on the map Outpost.
Here we have a brief look at every map in multiplayer that Bungie is allowing the media to show. This is a great video to get a feel of the style of each map.
Here's a video of Forge World. The first section shows the creation tools being used and some of the ways to construct a level. Then at the end he shows a brief tour of some of the map.
And finally here is a free for all Slayer match on a map built in Forge World that will ship on the disc called The Cage.








