It would really put the gov in a tough spot, and bitcoin would have an upper hand either way.
Unless they decide to prosecute users of BTC.
Really neat idea though -- were you thinking QR scanner and client integrated into an app?
That crossed my mind as well.... But it has to cross that line sooner or later, and i doubt theyd make a big deal out of it until its already a big deal. How can they prosecute giving a worthless gift, unless they consider it to be 'minting'? From what i understand, in the U.S., its legal to make a fake dollar as long as it is clearly fake, but a fake metal coin is a crime.
Hadn't really thought about it as an app - i was thinking just a url and a qr for that url, so it wouldnt be phone specific. You would buy 'x' cards, and they would be linked to your account. You pre-deposit btc on your account. First time you scan a card, it lets you put as much of your funds on as you want to give, then you hand out the card, and when they scan it, it asks where it should go. Buying the cards would pay for the site.
But an app with a reader and btc client would be nice just for ease of use... If someone were to whip up a little bluetooth thermal printer that would fit in your pocket, that would be pretty sweet too.