Hi,
I've written a thin client for iPhone, based on the idea of separating a peer node into a 'thin' client and a server. The client runs on an iOS device and doesn't need to download any blocks/headers from bitcoin network. The client just needs to download its transactions from server into its local wallet. NO PRIVATE DATA OF BTC IS SENT TO SERVER.
The client signs on its sending transaction LOCALLY and then sends to server which relays/broadcasts it to bitcoin network. The server pushes transactions to the involved clients (sender and receivers) .

MIT Licensed open source: https://github.com/fingster/BTC-Express
UI partially based on: https://github.com/udibr/bitcoinApp
More Details: http://forum.bitcoin.org/index.php?topic=31362.0
Beta version download: http://www.megaupload.com/?d=9RX93T9V

any suggestion is  welcomed, ;p

Best regards