Halo 3 Beta Supports 2 Player Splitscreen.

Here some good info right from Bungie's newest WWUD:

We have to make sure that Halo 3 scales well to a large population, and that will help us improve and test our netcode, as well as try out one more feature that we’re including in the Beta. A feature that definitely requires a lot of stress testing in a big population. Conspiracy theorists can drop their 128-player game theories at the door. Halo 3 is still a 16-player game, and the reality is that most people prefer smaller games than that.

No, this feature we’re testing is for the moment, just a fun addition, that’s planned to grow into something pretty amazing by launch, and that feature is Saved Films. The version you’ll try in the Beta, is very, very, very limited. We just want you to play around with the general concept. You’ll be reading more about this in the gaming press in the next month or two, and of course you can try it out for yourselves in less than a month.

As for the Public Beta itself, it’s pretty close to finished and a lot of folks have worked really hard to make it happen, with late nights, early mornings and a constant diet of Cheetos and evil. So to those brave men and women who sacrificed themselves on the Anvil of Bungie, under the Hammer of Crunch, we salute thee. Your smeared remains will be remembered.

Although the Public Beta may seem like a simple sampling of the MP levels from the finished game, extracting those and packaging them into a playable bundle, with off-schedule bug testing, gameplay tweaks, code fixing and netcode support, is a herculean task. Hopefully it will pay dividends and players will get tremendous enjoyment from these maps and game types.

Since we’re testing matchmaking, you won’t have the kind of control you’re used to with custom games, but we’ll be there to guide you into a very nice selection of Matchmade game types – and don’t worry, the playlists will almost certainly have your gametype in there, in some shape or form.

You’ll also be pleased to hear that split-screen will be an option, although limited to two people in the Public Beta. We’ve also done something cool with the splitscreen display for HD monitors – instead of stretching the horizontal or vertical axes into big, scary too wide or too tall horrors, we’ve sensibly windowed the action, maintaining lots of screen real estate, but preserving a proper, playable aspect ratio.

The most notable, I think, is the last paragraph here about splitscreen. I guess they're not going to do the "standard" type splitscreen of just plain old horizontal split. Well, at least they're not going to that god awful vertical splitscreen (/cough Rainbow Six: Vegas /cough).

(Via: Bungie.net)