Dear IRS: Bitcoin is like cash that exists, and can be spent, in two places in the world at once. Or 20 places. Or 10,000 places at once.

I have decided to share my private key with 28 of my most trusted friends. We come from 14 nations around the world.

I alone do not have the authority to spend those coins, only by a two thirds majority decision, can any coins be spent.

If Bitcoins are property, as you say, this private key and the blockchain address it accesses are now "communal property" of people all over the world

You can't tax it without United Nations authority, I guess.