I'm considering it (I have a registered business already in the process of accepting bitcoins), however for me any bitcoin bank should honour a charter/code thats in line with the bitcoin ethos. Apart from writing the software, this imho is the first thing that needs defining before going into the bitcoin business.

Currently my proposed banking charter would be

• 100% loan backing : Every loan of 1BTC is backed by a reserve of 1 BTC
• Transparency : Real time view of the banks reserves, so as to prove viability
• Saving separate from Loan/investment : Any savings/investment are in a separate reserve which is protected and paid back in case of collapse (no risk to savers)
• Minimum digital protection guarantee : Numbers of copies stored, encryption levels, access rights, etc.
  

However these conditions will make it much less profitable to be a bank than traditional bank, whilst many may see that as an issue it also means its less a 'gold mine' opportunity so likely to develop fast.

Profits on loans are simple and easy, either traditional interest or another scheme fitting those who cannot pay interest (certain religions)
Savers will expect interest BUT a 100% no touch policy would mean no way to generate interest. I'd suggest an agreed use percentage and a interest level based on that. i.e. a saver agrees to allow 20% to be used by the bank and in return gets a 1% interest return on the entire savings... (number plucked out of the air for example only).
For those who just want to use banking current account facilities, perhaps a small monthly fee to covers running costs?
Bank would also be an ideal place to run community investment and loan systems : Peer to peer with the bank offering certain guarantees and escrow services...

Just my ideas so far, would like to hear what others think and what they would want of a bitcoin bank...