From John Nack’s “Adobe Snow Leopard FAQ”
Surprised and disappointed that you haven’t tested it on CS3. It’s not exactly 5 releases previous is it? [I found that really surprising, too, and I'll try to get more info. I'd frankly be shocked if people at Adobe & Apple really hadn't tested CS3 on 10.6. I *think* it's just some corporate conservatism at work here, and Adobe doesn't want to over-promise anything. As I say, though, I'll try to find out more. --J.]
If only we knew for sure…I’m not ready to put down $500-600 for CS4 if CS5 is potentially out early next year. Snow Leopard should arrive on Friday (Pre-ordered from Apple), I might have a better answer by then.