Apple - Is there a hard keyboard case for the iPad keyboard?

I couldn't find any hard cases, but Waterfield/SFBags makes some nice soft cases you can use for transporting your Apple Bluetooth Keyboard:

_{(source: sfbags.com)
(source: sfbags.com)}

I really like the inCase Origami Workstation because in addition to protecting the Apple Bluetooth Keyboard, it unfolds to support the iPad in a comfortable typing position.

Andy Ihnatko included it in A spring selection of iPad-friendly accessories worth a look

Apologies for the commerce link above. The link is to the manufacturer's site and they don't separate product from store. The Origami is widely available from a number of sources—I picked mine up at a local Apple Store—and no endorsement of inCase as the retail outlet is implied.