Not a lot of sessions about SharePoint at PDC08 - but if you look very hard you will find a couple :-) ...
- Dublin" and .NET Services: Extending On-Premises Applications to the Cloud
- FAST: Building Search-Driven Portals with Microsoft Office SharePoint Server 2007 and Microsoft Silverlight
- SharePoint 2007: Advanced Asynchronous Workflow Messaging
- SharePoint 2007: Creating SharePoint Applications with Visual Studio 2008
- Sharepoint Online: Extending Your Service
For more details check out Paul's blog.