Sorry to have to break the news but Apple is not releasing OS 3.0 before the new hardware comes out. Early July it'll be available.
Yeah, and that went over SO well last year.
DOUBT IT!
I'm pretty sure they learned that you can't release everything on the same day.
Last year on July 10-11 they released:
iTunes 7.7 (with support for 2.0)
App Store
MobileMe updater for OS X
MobileMe
iPhone 3g
2.0 Software for iPhone 3g, iPhone, and iPod Touch
There were tons of app crashes, server crashes (MobileMe and activation), and tons of headaches (Apple Logo of Death anyone?). Apps took sometimes 10 minutes to install, the keyboard was sometimes unusable, especially in the SMS app, Contacts was so laggy, and the iPhone would reboot itself randomly several times in an hour.
I know not all of these problems can be planned for in advance, but last year's pile of releases was too much. They have already broken from last year's release by sending out iTunes early, which is compatible with 3.0. They are also testing their servers in advance this year so that the whole thing doesn't come crashing down when 3.0 rolls down the pipe. They are taking a lot more precautions this year, and one of those is probably "beta testing" the public with 3.0 on existing hardware for a month or so before iPhone 3rd gen comes out. It will probably be a lot more stable than 2.0--they've learned a lot since then and have optimized memory management, etc. But if there is a problem, they can patch an update to be ready. I'm not sure how able they are to update software on iPhones in production or sitting in warehouses, but at least it could be available for launch when they activate in iTunes.
Plus I REALLY want 3.0 before my honeymoon on the 14th. We're taking a long road trip and turn by turn GPS would be great. Hopefully TOM-TOM (or similar) is finished by then. Maybe they will be demoed at WWDC?