WWDC
1. You shouldn't want it sooner because there are bugs still. This isn't rumor, it is fact. Yes, they likely have a more recent version in house but these bugs are out on many different types of systems. I'm pretty sure they will want to test at least some fixes to some major bugs before going GM.
2. 10.4.9 is not released yet and I highly doubt, can't remember if Apple has EVER released a newer version at the same time as the .9 version. I can see 10.4.9 released in a few days or weeks. Then a month or two between and announce at WWDC along with the snazy new iPhone so you can show off all the cool features again.
3. Typically, Apple makes the .9 version the latest version they support and works with all updated software they make (i.e. the majority of Apple software requires 10.3.9 or higher).
4. WHY announce along side CS3? This makes NO sense except for those of you who have no business sense. CS3 is going to be big for Apple and many NON apple people. Why share some of the spot light with Adobe? You want them as a partner, sure, but you don't want them hogging your press (or worse, vice versa because you are hoping it will drive hardware sales of 10.4 systems). This is pure FUD. It makes absolute 100% no sense. NOT going to happen.
5. As it has been said, June is still Spring. They didn't promise March or April, only Spring. Anything before June 21 is spring. And if iPhil's info above my post is correct, then late spring makes even more sense.