I wouldn't describe them as a new format, but maybe as a virtual variation on traveler's checks. Paypal, which I use and find convenient, is one of those entities whose main profitability will prove to be for those who got in on the ipo. In the meantime, they make some money from some transactions, and from interest on your deposits, but without the great scale of a major credit card company. Add all this up - and bear in mind the problem of offering FDIC insurance while denying they function as a bank - and you will know to keep only as much on deposit as you can afford to have tied up for awhile if there's a meltdown, a la Martha Stewart, et. al.
