I've been using Snow Leopard for a few weeks now with our corporate Exchange server and I'm pleased to report: it just works. Simply (far easier to configure Snow Leopard to work with our Exchange server than to set up a new copy of Outlook). Within moments of entering my email address and password, all my calendar items, contacts, email, and to-do lists were integrated into the appropriate Snow Leopard apps. I haven't had a single problem with the configuration.
For me -- as user who's used both platforms for years -- I've been constrained to using Windows mostly because Exchange worked so much better than Entourage did. With the introduction of the latest version of iLife and Snow Leopard, I find I'm not just doing my creative stuff on the Mac, but am able to fully migrate my business use as wellI've also been running Snow Leopard and using it with Exchange and agree with his sentiments. The integration is as good as it is on the iPhone; it just works and in some cases works faster and better than my other MobileMe account.