I use Verizon. And for anyone who doesn't know, most Verizon phones have a basic delivery confirmation program that works for M2M (mobile 2 mobile, aka Verizon to Verizon). If the receiver successfully received your message, a small check mark appears next to the text on your phone. If their phone was off or for whatever reason they didn't get it yet, an arrow is shown indicating that they have not yet received the text. Besides iMessage, is there a jailbreak app that would show a similar type of delivery confirmation for non-iPhones on M2M?