So current Maemo 5 non-QT binaries are forward compatible with Harmattan and Meego (I separate the two because Harmattan is Meego compatible even though they're calling it Meego)? If so then I am relieved thanks.
That wasn't what mooninite said - he said that anything he develops will work on both. Current non-Qt apps is questionable - GTK+ will still be supported on MeeGo, but not necessarily with the Hildon extensions. That would seem to be (mostly) going to be up to the (ex-)Moblin developers, as GTK+ support appears to fall under their remit.