Here’s a cool little gem I just found in Exchange 2007 in SBS2008.
You can access the server (or other servers) shared folders from OWA by enabling Remote File Servers in Exchange 2007.
1. Open up Exchange Management Console, Client Access, and Properties for Outlook Web Access.
2. In the Remote File Servers tab, Click on Allow, and add the file server name.
In Outlook Web Access, click on the Documents tab. Click on Open Location, then type in the file share location in the form of \\servername\sharename.
*** UPDATE August 2010. Unfortunately, Microsoft disables this feature in Exchange 2007 SP3, and also in Exchange 2010.