Using 2x 8800 GTX in SLI?

[4GHZ_or_bust]

About a year or so ago, I remember an article in MaximumPC that covered 8800 GTX that has 2 GPU in one card and could run in SLI mode while using only 1 PCI-e slot. They claimed back then that using 2x 8800 GTX won't work because quad GPU wasn't supported.

But just recently while looking through eBay, one auction stated it can be done. Has it changed? Or is quad GPU still a problem?

Also is there a list somewhere of the dual GPU card that can run in SLI mode and needs only 1 PCI-e slot?

Thanks.