Index Card (singular) is "a simple, but powerful, non-linear writing tool designed specifically for the Apple iPad. Capture your ideas and store notes as they come to you. Organize the flow of your project by using a familiar corkboard interface. Compile your work into a single draft document that can be read by most word processors and specialized formatting programs. Index Card will assist in writing, structuring, and managing a large project by allowing you to work in small easily manageable chunks." (their claims).
Looks cute, but I doubt it is more useful than Notational Velocity or other more minimal tools.
The Website also says: Index Card "projects with the award-winning Scrivener application running on your Mac OS X computer." Don't know precisely what that means, but it seems to to refer to the claim: "Starting with Scrivener 2.0, you can sync projects with Index Card. This includes the title, synopsis, and order of cards in your project. The folks at Literature & Latte have put together a fantastic video on how to sync Scrivener with Index Card for iPad."