SharePoint SP1 fixes over 250 specific issues listed here: http://bit.ly/SPSP1Fixes
· Support for SQL Server Code Name “Denali”
This will enable you to run Denali on a SharePoint server.
· Shallow copy functionality
This enables you to move Site Collections between content databases using the PowerShell command Move-SPSite.
· Site-level recycle bin
You can recover entire Site Collections and Sites that has been deleted.
· Improvements to storage management (StorMan.aspx)
This enables users to manage the amount of storage they are consuming.
· Cascading filters for Performance Point services
This enables you to chain filters together by passing values.
· Additional browser support
IE9 and Google Chrome are now officially supported.