1. A computer program product comprising one of more computer-readable media having thereon computer-executable instructions that, when executed by a computing system capable of running a continuation based runtime, causes the computing system to perform a method for allowing the continuation based runtime to participate in a transaction without having generated the transaction, the method comprising: an act of marshalling transaction data for an externally generated transaction into an activity within the continuation based runtime; and an act of the continuation based runtime using the marshaled data to perform an internal portion of the transaction.