Yea, that's curious... I got my info from a user of my plugin who changed his icon. I just passed it on. I don't have a high res iPod or iPhone yet.
I just tried it again with the SMS plugin to verify I really did it right. I did, but it does not work. It used to work with Retina icons on some previous version of LockInfo. Quite curious!
Since I switched over to using WinterBoard to do this I have not really paid much attention to how the icons worked since changing them always works using WinterBoard.
S-