AT&T and T-Mobile users have been able to have their Android Market purchases billed directly to their wireless account for awhile now. Sprint is the latest US carrier to join the party, which means its Android users have one less place on the internet they have to store their credit card number:

The momentum continues and today we're excited to announce that Direct Carrier Billing is now available on Sprint. We've begun a phased roll-out of the service that will reach all users in the next few days. When complete, Android users on the Sprint network will be able to charge their Android Market purchases to their Sprint mobile bill with only a few clicks.

We believe that Direct Carrier Billing is a key payment option because it lets users purchase and pay for apps more easily. It's also important because it offers a convenient way to buy in regions where credit cards are less common.

[Android-Developers]