we're also adding a new 2 vs. 2 playlist called "Double Team."...On some maps, like Coagulation for example, game types have been revised to include a BR/SMG start. We have not done this to all maps and game types, just the ones where it makes the most sense. Your cries for more variety have been heard - we've added game types such as "Snipers" and more instances of "Rifles" to appropriate maps as well as adding Covenant vehicle varieties to existing game types. Everyone wanted to see the Spectre and now you will. The sudden death timer in Assault games is being turned off to prevent extended griefing and dragging games out to insane lengths. In lieu of the sudden death timer, we've increased round times by one minute. The unranked playlists (Team Training and Rumble Training) are getting a bit more experimental with new game types being added (Slayer Pro, Golden Shower, SWAT, Brutes, etc..). The list of tweaks goes on and on but that should give you a good idea of the types of things to expect. We'll be updating the playlist page on Bungie.net with the explicit details once we're ready to make the update.
http://www.bungie.net/News/TopStory.aspx?story=weeklywhatsapril22&p=3106844