SharePoint as you might know renders content in much more standard ways. It’s accessible, it’s XHTML, etc., and this means that users on non-Windows platforms will have a much better experience with most SharePoint content! This extends to mobile platforms, like phones–I browse my own SP2010 site with my iPhone, for example. And the new Windows Phone 7 will have integrated SharePoint support.
For offline functionality, SharePoint Workspace (formerly, Groove), provides a rich experience with lists and libraries offline. Access 2010 can take data offline (as could Access 2007/SP2007), and outlook can take certain list types offline (contacts, calendars, tasks, e.g.)
<i>This question was answered by Spencer Harbar, Enterprise Architect at Microsoft and Dan Holme, Consultant and Trainer, Intellium.</i>