I must say I thoroughly enjoyed the "Playlist of the Living Dead" extravaganza yesterday on Live. The infection gametype has always been one I've enjoyed, from its latest iteration in Halo 3 to the older iterations in games like Perfect Dark Zero and the TimeSplitters series. To me, it's more interesting than a standard deathmatch but doesn't actually require much strategy or teamwork, like some of the team games. It's a happy medium that doesn't appear often in the ranked rotations.
I would love to see the All Infection playlist get permanent placement among the other ranked playlists. I know many people would opt to play pure infection as a ranked alternative to slayer or team slayer. Given that the number of players is significantly more than the Lone Wolves playlist, it makes for a more "fun" big atmosphere. A possible alternative here would be a Lone Wolves 8-13 size ranked list, where infection is sprinkled in. Another point is that people like to be able to play ranked with their friends, and the allowance to have a party of 4 join the ranked lists was a great addition.
In conclusion, I'd love for the all infection list to become a permanent ranked list for Halo 3 multiplayer, or in the alternative, a large (8-13) Lone Wolves list where infection is roughly half the games.