So I went to the customs office (in Malta) to get the merchandise I bought online with Bitcoin. They ask for a Paypal receipt (?!) or an invoice. I don't have either of them, but they say they'd accept a printout from the web site's order page. In a hurry I get a print out and hand it. They ask me what BTC is. I blabber something unintelligible to get it over with, but they go and check anyway. They tell me it's Bitcoin and the exchange rate is ~2.99. I pay my customs tax and get my box.
I'm pretty excited about this, and interested in others' similar experiences. Also, I don't know from which source they checked the exchange rate, so what do you think should be the authoritative source for government entities? Which generic sources publish BTC exchange rates?