Something doesn't smell right here. Why would Adobe's CEO go out of his way to tell a news agency that they can't guarantee CS3 will work properly with Leopard? I'm going to go out on a limb here and assume Adobe has an ADC membership and so has access to the so-called feature complete beta that Uncle Steve released at WWDC (or rather the subsequent builds). While it may be strictly true that Adobe hasn't received a gold master, neither has anybody else as far as we know. Nonetheless, can't they have "fully tested" CS3 with the builds that they presumably do have? In fact lots of people already have Leopard, so it can't be that big of a mystery whether CS3 is compatible.
My guess is that this is another flare up of the increasingly tense relationship between Apple and Adobe, and that Adobe is just trying to publicly remind Apple that a lot of people will hold off on Leopard until they can be sure that Adobe's products are fully supported. In other words, this is a little bit of breast beating on Adobe's part and the implicit message to Apple is that for a lot of pro users our stuff (CS3) is more important than your stuff (OS X). Particularly given the rise of iWork '08 (and the implicit slight to Microsoft it represents), I'm sure Adobe wants to make sure Apple remembers what's important vis-a-vis third-party developers. Whether Apple will take kindly to the message is something else entirely. What do you think?