1. A method for providing users with an application with in-application purchasing functionality, and for processing purchase requests resulting therefrom, the method comprising: receiving, at an application repackaging system associated with an electronic catalog, a submitted application; decompiling at least a portion of the submitted application thereby creating application source code; injecting, into the application source code, in-application purchasing source code associated in-application purchasing functionality, thereby creating modified source code, wherein the in-application purchasing functionality provides for in-application purchasing of items from the electronic catalog; compiling the modified source code to create a modified application including the in-application purchasing functionality; making the modified application available in the electronic catalog to end users; receiving a request, from a computing device of an end user, for the modified application; providing the modified application to the computing device of the end user; receiving, from the computing device of the end user, a purchase request for the purchase of an item available through the electronic catalog, said purchase request generated in-application with the in-application purchasing functionality of the modified application; and processing the purchase request, said processing comprising providing the end user with the item; said method performed by a computing system that comprises one or more computing devices.