It seems that the
Kickstarter project Trsst will be using bitcoin addresses as its keypairs. From the
paper:
A keypair in terms of public-key cryptography is the pair of a private key and its corresponding public key. Each user's account corresponds to a keypair, and the public key is the account's unique identifier. The keypair is generated as a valid payment address in a crypto-currency system such as Bitcoin. The account's private key is held by a user in secret and kept in a keystore.
I'm looking forward to see if this idea takes off and, if so, what relation it will have to bitcoin.