As of now, the Warriors are about to essentially trade Dorell Wright for Jarrett Jack in a 3-way trade. It's not official yet, but if the deal were to go through, the cap situation would like something like this...
*click for larger image
The rookie salaries are only estimates and Brandon Rush's Qualifying Offer will likely be adjusted later, depending upon what salary they agree to resign him. If these numbers are close, then the Warriors still have about $3.4M to play with before hitting the Luxury Tax threshold. That's theoretically enough to resign McGuire and a lower tier PF/C like Sheldon Williams.
Current Roster (if trade goes through)
PG: Curry / Jack / Jenkins
SG: Thompson / Rush
SF: Barnes / Jefferson
PF: Lee / Green / Tyler
C: Bogut / Biedrins / Ezeli
2 open roster spots
Needs: backup PF/C and Dominic McGuire