A bulging wallet used to be an item of envy because it would almost certainly be filled with money. That's what a wallet used to be for: keeping notes. These days you can tell a lot about a person by the things he stuffs into his wallet: bank cards, credit cards, licence cards, employee cards, membership cards, discount cards, coupons, and what not. Standing at the cash register, I have noticed that the more bulging the wallet is, the fewer dollar notes it seems to contain. The idiom about a fat wallet no longer holds true.
The bulging wallet may be put on a diet soon. Google and Apple are both racing to make the Android and the iPhone the means of making small transactions. At the same time, three of the four largest mobile phone carriers in the US have teamed up, and are inviting banks and retail outlets to join them, to turn phones into digital wallets. This was supposed to be one of the key features of the Newton, Steve Job's PDA that was way ahead of its time. I believe the time is ripe now for this to happen within the next couple of years.
Looking back, I must say that from the wallet perspective we can now look forward to the good old days where a wallet is a wallet, and not a miniature carry case anymore.