[quick99si]

It looks like they do pretty extensive auth on this (as expected):

Sprint Offering Carrier-Billed Android Market Purchases

If you have an Android phone on Sprint, now you can charge you Android Market purchases to your Sprint bill. The service actually started to roll out on April 7, and will be available to all Sprint customers by April 14. The option is already available to T-Mobile and AT&T customers.

Now, Sprint customers will automatically be given the option when purchasing an application in the Android Market to have those items billed to them on their Sprint invoice. Those charges will then appear on their next Sprint bill, where they will need to be paid, much like charges for voice and data services.

The “Bill to Sprint Invoice” option is not available on the HTC Hero or Samsung Movement, and Corporate Liable (CL) customers will automatically be opted out of the service. CL customers will still see the option to make the purchase on their Sprint bill, but if they have not opted in to the service through Sprint.com they will not successfully be able to complete their purchase.

Sprint Offering Carrier-Billed Android Market Purchases | TechnoBuffalo