A very simple question yes, but I haven't gotten to play beyond solo and I'm really curious - what happens when your teammate dies in a Co-op Campaign or Firefight match? I can't imagine a Gears style revival system. When a teammate dies do they just blink out till the next checkpoint/wave?
 
And before anyone says 'Google it' using 'Halo: Reach' 'Death' and 'Co-op' really only seems to bring up articles about 4GB SXbox360 not being compatible with Co-op.

Campaign - After you die, your teammate has to get safe for you to spawn back in. If he's fighting, or under fire, or is too close to enemies, you won't spawn back in. You have unlimited chances, as long as all of you aren't dead at the same time. 
 
Firefight - You have a set number of lives. No matter where you die, you'll spawn back at the area where you start. Once you run out of lives and die, you must wait until either your teammates earn you another life by finishing waves, or you wait until they all fall.