Profile Properties and OWA in SPS2007
There is a new Profile Property called "Outlook Web Access URL" that can be very handy. As you may already be aware, there are various OWA web parts that show information like Mail, Calendar, and Contacts using Exchange OWA. If you fill in this field then these web parts will use it for their OWA URL (although you still need to enter in the username).
As an added bonus, there will be a new link added to the user's "My Site" menu bar called "My OWA" which will redirect the user to the Exchange OWA site.
As it stands right now this field would need to be filled in for each user but I imagine with some Business Data Catalog mapping, this could be done automatically saving your users a rather annoying step.