The funny thing when I bought my new Sapphire 5870 X-Vapour OC is that I never really realized what eyefinity was.
One thing I can say now is that the guys at Matrox with their Triple head go must be PI$$ED off.
Their over prised technology in my opinion is obsolete if you have a ATI with eyefinity. I've always wanted to get it, but the price was always a no sale
I think Eyefinity is going to be one of those things like getting the TrackerIR and wondering how you got by without it for so long!
I've already tried it with my two monitors ant it works a treat. I'll update when I get my third monitor.
Here is a few links to those who are interested.