Thanks to the incredible efforts of francois.guilleme, the iPhone finally has delivery reports!
By intercepting calls to/from CommCenter, his library modifies outgoing SMS headers (adding the delivery report flag), and captures incoming SMS reports (displaying them either as a flash message, a regular sms message, or a simple ‘tick’ mark).
All the details (including source) are up on the google code site. Installation is simple, just add
http://iphonedelivery.advinux.fr/cydia as a cydia source, install the
iPhoneDelivery package, and robert is your relative.