Follow the link and read, you will find that it is indeed an IDE channel off of the Promise SATA chip.
Serial ATA
Supporting Software RAID 0, 1, 10(opt)
Promise S-ATA controller 2 S-ATA, 1 P-ATA
I think that the MSI Canterwood board has this same Promise chip on it too. It does 2 channels of SATA and 1 channel of P-ATA.