No more than 3 cubes per 20A circuit. If you put 4 cubes on a 20A circuit you *will* have problems. Not in all areas, but in enough that you'd be kicking yourself. Most people will be fine with 2 duplex receptacles, but a few will need more. If you have modular cubes, either buy extra receptacle modules to plug in for these people as needed, or buy some surge supressors. (Not power strips, they're not legal! Surge supressors, however... gold!)
Each laser printer or copier will need a dedicated circuit if you go by strict NEC, though 2 can share without much issue. Be kind and put in a dedicated circuit for the coffee maker/microwave area, too.
