I completely missed this announcement from the Microsoft XML team a month ago, that they will release an XML Schema Designer for VS2008. What can I say - finally!

See a short video here. 

Download the CTP here. 

It looks promising so far, but I'm still waiting for some screenies of the graphical view of the designer.

EDIT:

I snapped up this from a forum post:

The original schema designer in VS has been removed from the product.  There will be a new schema designer, but it will ship in off-cycle release after the Orcas is shipped.  Currently, you have to use VS2005 to edit the schema file, or use the Xml Editor, which looks like a text editor, but does provide intellisense and schema validation.