December 11 Update
The December 11 playlist update is well into testing. This playlist is going to include a playlist specifically for the new Heroic DLC maps (so that early adopters can get their fix in), as well as incorporating those maps into the general playlists. In addition, we're reasonably sure that variety updates to almost all of the playlists will be included.
December 18 Update
An extra week buys us some extra testing time. The December 18 update will include the Team Hardcore playlist. I will post some specifics about the composition of this playlist by the end of the week--we're still playtesting. What I can be pretty sure about is that we're trying to stay true to Halo 2's THC playlist, which means nothing crazy, but a solid variety.