This bank "overlay" concept appears to be very similar to what SmartyPig (http://www.smartypig.com) has been doing for a couple years. The revenue model is slightly different (SmartyPig partners with retailers to offer cash back bonuses to customers if they convert their savings goal into a retailer gift card or load it on to the SmartyPig Cash Rewards Card), but the general model of leveraging existing banks for client deposits is the same. I will be interested to see how competitive BankSimple's interest rates are and if they can differentiate themselves in a meaningful way from the many great online banks that already exist (INGDirect, Ally, etc.).