Just had a good look at the manager's iPad launch date plan book.. I know there were similar images posted on tuaw, but I didn't see any that listed the cases. Looks like Targus and Incase will be introducing cases on launch day.
I checked employee pricing, and unfortunately the iPad SKU shows a costs of $0.00, which means it will probably be $499 for everyone. The iPad dock however was only $24, so I'll get a bit off on that.
Just thought I'd share!