The current schedule calls for RC1 to be released on or shortly after September 7th and it to be RTM no later than October 25th. That gives them less then 7 weeks to fully deploy RC1, receive the feedback, make any necessary adjustments, and start cranking out CDs for its volume licensing customers. Thus, it's entirely possible that there won't be an RC2 for Windows Vista, something that's not currently scheduled, and no time for an RC3. Unless their team works overtime for the next two months there will be a lot of critical updates awaiting consumers when they pick up their copies in January.
I always thought there was two, but I heard a rumor stating that there will be a third. Can anybody confirm two RC's