For those interested: Western Digital already had their Black, Blue and Green line of harddisks, but now they have Red as well. WD claims these drives contain special firmware, meant for optimal performance in combination with NAS'es. They say they have developed special "NASware" firmware. No idea what would make these disks more special than their other drives. (Maybe Mark can answer that one for us?) They come in 1, 2 or 3TB, are SATA600 and have 64MB of cache, so pretty average in my book.

Edit: you can find the first online review on the 3TB version of these disks here.