Another update to the Deep Zoom Composer has just been released. This release only contains fixes to issues that were reported to the team. More information on these fixes can be found on the Expression Blend and Design team blog.
Not sure on how to use Deep Zoom Composer? Check out the User Guide. You can access this by going to Help > User Guide or by pressing F1. Any ideas for future Deep Zoom Composer releases? Let the team know here!