See https://en.bitcoin.it/wiki/Scalability https://en.bitcoin.it/wiki/Scalability. It is true that the network would have to evolve to a two-tiered structure w

See https://en.bitcoin.it/wiki/Scalability https://en.bitcoin.it/wiki/Scalability. It is true that the network would have to evolve to a two-tiered structure with supernodes and client nodes. In Satoshi's paper it is explained how low-power client nodes can do "Simplified Payment Verification" (Section 8 of http://www.bitcoin.org/bitcoin.pdf http://www.bitcoin.org/bitcoin.pdf). This is the mode implemented by bitcoinj (http://code.google.com/p/bitcoinj/ http://code.google.com/p/bitcoinj/) and it is already used to run bitcoin clients on android.