Unpainted Halo miniatures from the Halo ActionClix set.
Halo ActionClix was announced on the 2nd of February, 2007. It is said to bring brand-new game mechanics to the WizKids Clix game franchise, such as weapon swaping, figure respawning and vehicle-based combat. The set is said to include 80 minis and contains a few preview miniatures for Halo 3.
A number of vehicle packs are being made, as well as a surprise for San Diego Comic-Con this July. Figures are to be sold in randomized booster packs, where the vehicles and starter set are to be sold in a diorama display format.
The Halo ActionClix CMG is expected to be released at retail in September 2007, with special Prerelease figures available at San Diego Comic-Con July 26 - 29, and at Gen Con Indy August 16 - 19.
I've included some basic info on the factions here:
More info is available on the  Halo Wiki.