Head over to the Microsoft web site to get your update for Expression Design.  From the original post:

What's new in the Service Pack?

Highlights of XAML Export improvements and fixes

  • The XAML Export UI has been updated to make it easier and more intuitive to select the desired export settings.
  • Text can now be exported as TextBlocks for Silverlight applications.
  • In the release version of Expression Design, all objects were given default names. Naming objects is now optional. When the "Always name objects on export" option is not selected, only objects you have explicitly named in Expression Design are given a name on export.
  • Gradient midpoints are now exported.
  • Since the release of Expression Design, the direction of the slashes in filenames for Silverlight applications has changed. Expression Design now writes out forward slashes in filenames and paths for Silverlight and WPF XAML. 

Highlights of other issues fixed

  • Anti-aliasing can now be applied on export to large images.
  • The quality of image export has been improved.

Go get your update today!

Expression Blend and Design : Expression Design Service Pack 1 is now available!