Apple just updated its store with some more information about when, exactly, we can expect the iPad 3G to ship in the U.S. The company's exact wording is "by May 7th," which suggests that some iPad 3Gs may be delivered before that date.
As far as international availability goes, there's nothing new in the Apple Store about that. Apple will announce international pricing and begin taking online pre-orders on May 10, three days after iPad 3G starts shipping in the U.S. Let's hope Apple doesn't sell out its stock again by then.