Yesterday (10/19/2011), the 343i folks released an updated "Halo Bulletin" containing the multiplayer achivements:
http://halo.xbox.com/en-us/news/headline/the-halo-bulletin-101911-/290604A total of 250 gamescore points have been added across the seven new achievements, bringing the game up to a total haul of 1250 GS.
I have added these to our
index.
Top Shot - 50 points
Get 3 headshot kills in a row in a matchmade game.
Emergency Room - 15 points
Infect 3 players in a single round in a matchmade Infection game.
Stick it to the Man! - 20 points
Stick and kill the flag carrier with a Plasma Grenade in a matchmade game.
Dive Bomber - 50 points
Perform a Beat Down on an enemy player while using the Jetpack during a matchmade game.
License to Kill - 15 points
Run over 5 people with a Ghost in a matchmade game.
Bounty Hunter - 75 points
Capture 10 skulls at once in a matchmade Headhunter game.
From Hell's Heart - 25 points
Kill an enemy player that sticks you with a Plasma Grenade with their own grenade in a matchmade game.