Flash on OSX Lion is a TAD BIT BUGGY right now. That's not lost on Adobe, and they've posted a document of all known issues with 10.7. One issue they suspect, but can't prove: Apple disabled hardware acceleration with Flash.
Apple made the bold move of pre-announcing its WWDC offerings last week, but we're sure there will still be surprises aplenty. Be sure to check out our liveblog today for breaking news; in the meantime, here are our predictions: