Over at IGN they are reporting that Microsoft has told them that the upcoming Halo: Reach multiplayer beta will run from May 3rd to May 19th.
They also report that Bungie will be turning on certain playlists of the beta at certain times throught the 17 day period.
When fans start up the beta through their ODST game on Monday the 3rd, they will have access to the Arena Mode, a 4v4 ranked Team Slayer, a free-For-All playlist and also a new grab-bag playlist that will be a mix of classic and new game types.
There are 2 unique modes that are scheduled to be released on May 7th and may 14th. They are called Invasion and Generator Defence respectively.
Last but not least, to those who own an ODST disc, there is a beta introduction available tomorrow via the game disc, so be sure to boot up the game and check that out.