According to the site it is NAND flash. Of course, how they could sell theirs for a little over half of what the competition charges is suspect. Super Talent's site doesn't even mention CF cards, though
I found a review for a 1GB CF card of ST's that wasn't very helpful, just said that 1GB was great for lots of pictures I also found reviews of their PC memory modules, and some other misc PC hardware, and people liked them in that area and said they made a quality product.
I dunno, I'm somewhat skeptical, but it's out there in case anyone is interested and/or knows more about the company(s).
Amazon has those regular 4GB Sandisks for $150 and Ultra IIs for $180ish, and those are both reputable places