The first part is basically what Final claims to be doing:
1. Use your real card number. I never do this. 2. Use a merchant-locked card number. I use this commonly for online pizza and other online shops I don't trust much. Once a merchant uses it, only that merchant can use it. 3. Use a one-time card. The number is used once and disabled. Good for one-off orders or skeezy purchases.
Overall I've been pretty pleased. I think the idea that card numbers should be disposable is awesome.
edit, i checked it out. so 1) its no open to sign ups, and 2) you have to have pretty stellar credit to even be considered. so that leaves out most people.