I was not aware how awesome the MSI NX8600GT Twin Turbo was until I read this article at [H]ard|OCP. The page for the card at MSI's site does not tell you about this sweet overclocking button on the bacl of the card. However, this page does.
The button increases the GPU, memory, and shader speeds from 540MHz, 1400MHz, and 1450MHz to 580MHz, 1600MHz, and 1508MHz when pressed and then swithces it back when pressed again.
MSI's press release also states that because there are two BIOS chips on the card, enthusiasts can create their own overclocks on one BIOS chip and revert back to the other chip if something goes wrong.
"...the NX8600GT Twin Turbo, has two separate vBIOS on-board which carry two dedicated GPU/Shader/Memory clock settings. Users only have to press a hardware button on the bracket, and then the new (higher) clock setting can be applied without re-flashing the vBIOS chip. Also, these two vBIOS chips give extreme enthusiast a Die-Hard workability (another vBIOS chip as spare) if they want to tweak the vBIOS to find out the ultimate performance parameters between Shader clock and GPU core clock."
So this card is pretty unique. Overclocking button, dual BIOS chips and it lets end users overclock the shader processor. The only question that remains is, how much will it cost?