1) Despite creating an actual style guide for the logo, including recommended usage, the proposal IMO lacks serious attention to typographic detail, the one thing a currency logo actually needs. None of the examples look particularly great: the type is misaligned, the text dominates the B logo in practically every badge.

2) The Wikimedia-linked B is much better designed as a shape, has the right weight, but the tacky coin presentation completely ruins it.

Someone needs to take approach 1 to proposal 2 and we'll all be better for it.

Edit: nevermind, someone already did: http://forrst.com/posts/Rebranding_of_Bitcoin-Ft5