[billyarzt]

Potentially dumb question: if there are 21 million bitcoins (and therefore 21 million bitcoin addresses), would that limit bitcoin's efficiency as a medium of exchange? Ie wouldnt there be potentially billions of transaction moving through a financial system powered by bitcoin daily? (Apologies in advance for any flawed assumptions).

[nathan7]

The flawed assumption is "and therefore 21 million Bitcoin addresses". Generate an RSA keypair, and give out the hash of the public key (encoded in a Bitcoin-specific way). Anyone can send you Bitcoins there now.