I guess the fundamental question is whether the mini-SD format supports 4GB in a non-SDHC format. If so, then some of these cards may be legit. If not, then it appears that they are 2GB cards that have been altered to somehow report 4GB, but cannot really hold that amount reliably (as some brave but unlucky people have been finding out). I tend to think that if the mini-SD spec really did support 4GB non-SDHC, you would see them being produced by the major manufacturers and being sold by mainstream vendors.