If they are marketed as a "real" physical representation of a currency, then that is how the prosecution would treat them (if such action were pursued). The vendor's own verbage would be the prosecution's case.

Indeed, they effectively have serial numbers.

I am just saying that Bitcoin is clearly on the gubberments radar now, and 'Bitcoins' being posed as physical coinage is not going to help.

The two legalese keywords here are 'novelty' and 'entertainment'.