Seeing that they released iTunes 8.2 prior to WWDC and saying that it supports iPhone 3.0 OS, it is very possible that they will release the 3.0 at or not too long after WWDC.... That's what I'm hoping for anyways
Don't do this to yourself! I've learned after 8 years of following Apple events that if you expect the worst, more often than not, you'll find yourself not being disappointed. We'll most likely see a Beta 6 released at WWDC after the new features are announced, if their are any, and then the final will be out in late June or mid July.
I also doubt BeeJive knows when the release is because I can't see Apple telling them that before WWDC. If they were telling developers this, I am sure more would've leaked out than what we've seen.