The only way to do 5x1 Right now is to use 5870 eyefinity 6 edition. Eventually the 6000 series will get the DP 1.2 MST hubs and you'll be able to get it that way. But honestly I don't think the 6970 is that big of an upgrade. I'd just go ahead and get a 5870 E6 on Newegg (open box deal right now).
I did just that myself. Picked up a PowerColor EyeFinity6 open box for $135 discount. I don't exactly like PowerColor, but it was the cheapest Eyefinity6 listed by $50. Wonder why ASUS thinks their OEM card is that much more of worth than PowerColor? :P
Probably sell off my spare GTX465 and one of my three GTX470's to offset the cost. That way I can still do both AMD EyeFinity and NVIDIA Surround for testing purposes.