Looks pretty awesome in my 5 min trial. Back of the card is very well done.

This will could go way beyond the software crowd to a general organization app..I just hope this thing scales well and they clarify their upload limits and such.

Edit 1: I tried their iPhone app and it's very far from their web interface - took me 6-7 clicks just to get to a checklist for one of the items. It's commendable that they have a app on launch though so I am sure they will work out the app interface with time - currently it's an order of magnitude less usable than their webapp.