It's not due until Fall; that's September 21'ish - December 20'ish in the U.S. That means they have a good 3 - 4 months of BETA, before they start chatting about Release Candidates, or whatever they happen to call the phase. There will be at least 5 - 8 more iterations of updates. In fact, the current BETA 2 is set to expire on 7.31.12. That means they'll have BETA 3 out a week, or so before that...
beta 3 will be in 2 weeks if they are following the pattern of iOS 5, with a launch of late October (think its around 20th from what people were estimating)