SharePoint Workspace capacity limits have increased for SP1. The approximate upper limit for documents that can be stored in the Ofice Document Cache before you can start to see significant impact on memory and performance, has changed from approximately 1,800 to 10,000 documents, depending on file size, type, and contents.

And, an update has been applied to Alternate Access Mapping handling as well.

For details, see:
http://technet.microsoft.com/en-us/library/ee649106.aspx