The "locks" around the edge (at least, I think that's what they are?) would never show up clearly if the image gets much smaller.
The coloring is pretty, but a bit.. "much".
The "current" logo:
http://utopianist.com/wp-content/uploads/2011/05/bitcoin-online-p2p-currency.jpgIs simple, it's not confusing (the "dollar sign" marks in the B itself lend itself to be viewed as a monetary unit), and... well, it works.
I like this better than the one in the OP, nothing small that's going to get overlooked or scrunched too far.
