Improvements to SharePoint document libraries include: <br />
Similar to the functionality provided by public folders in Microsoft Exchange Server, e-mail enabled discussion boards support:
<br />
<ul>
  <li>Checking out documents locally</li>
  <li>Offline document library support in Microsoft Office Outlook 2007</li>
  <li>Major and minor version numbering and tracking</li>
  <li>Support for multiple content types</li>
  <li>Policy, auditing, and workflow</li>
  <li>Tree view support</li>
</ul>