You might have seen demos of Exchange 2007 and the Unified Messaging capabilities (which are mondo-cool and so great to demonstrate to people that they’re sometimes open-mouthed in awe): if so, and you want to play with it yourself, then check out this great new resource:
https://signmeup.exchange2007demo.com/
Put in your email address, and you’ll be sent the details of your temporary (5-day) logon to the system, accessible from Outlook Web Access, Outlook (using “Outlook Anywhere” aka RPC/HTTP) or from a mobile device using ActiveSync.
Oh and you get a (US) phone number to call to test out the Outlook Voice Access function, which allows you to navigate your mailbox and interact with it either using a phone’s keypad or (if you’re an English speaker), with spoken commands.
If you’re not US based, you could sign up for the Windows Live Messenger/Verizon Web Calling service, which would allow you to call a US number for a lower cost (in the UK, about 1.5p a minute).