If you get the following error when trying to register for a device token, firstly ensure you have correctly followed the directions within the iPhone Developers Portal.
Error Domain=NSCocoaErrorDomain "no valid 'aps-environment' entitlement string found for application"
I am currently in the middle of designing and developing an application based on the Apple Push Notification Service. There is alot of information about the client side registration and plenty of server side code examples, but I haven’t found anything that simple demonstrates how to send your device token to the provider service.