I can't understand the mystery around the subj but it seems that no one is developing tweaks in this direction anymore.
3 years ago there was Twirly SMS but their website and forums are dead, and Cydia apps outdated (they don't recognize iPad 3).
What's happened? Nobody's interested in this anymore or I missed some trivial self-made solution?
This is about native (operator) SMS support only. surrogate solutions like BiteSMS are not relevant.