One of the ways players will earn cR is with the new challenge system. Bungie will create daily and weekly challenges, small goals designed to keep players interested over the long term. The challenges can be anything, with Bungie's Luke Smith noting "kill X dudes" as an example. Whether said dudes be in multiplayer or single-player, that's up to Bungie.
The article also touches on the new ranking system. In addition to ranking players based on skill, the game will also track how they play. Players can earn "Commendations" which reflect their playing style. Make kills with a specific weapon and you earn Commendations for that weapon, which other players can see. Commendations can be earned for other actions too, like driving vehicles.
Finally, Microsoft has announced that new Halo: Reach multiplayer info will be dropping every Friday between now and the launch of the multiplayer beta in May. The updates will appear on Bungie.net starting this Friday, so be sure to keep your eyes peeled (for jet packs).