UK (Royal Mint) about putting them on Coins:
http://www.royalmintmuseum.org.uk/FAQRetrieve.aspx?ID=49899Dutch National Government about puting them on Euros:
http://www.rijksoverheid.nl/onderwerpen/geldzaken/eurobiljetten-en-euromuntenFor what we know it is the same story for the US. Governments do not like it, but it's absolutely not illegal. Perfect for a piece of disruptive technology such as Bitcoin!
Might it be the case that you become scared within 30 days after purchase, you're always free to send 'm back.