I have an iPad, an old iPhone 3GS and a new iPhone 4S. When someone sends an iMessage to me it appears simultaneously to both my 2 iPhones but does not appear on the iPad. When I respond from the iPad the message appears on the iPhones.
A friend has a worse problem where his new iPhone 4S does not receive any iMessages, instead the are only received by his old 3GS.
Is there a trick to setting this up? I have tried making sure that all the "Receive At" email addresses are synchronized on all devices. Could this be a bug in iOS 5.0.1?