if i'm not mistaken the eyefinity is exclusive to ATI HD5000 series only. nvidia 3d surround works for upcoming 400 series and current 200 series but you'll have to SLI your card to enable to use 3 monitor
I suppose a solution like nvidia's would be possible via software, the same way nvidia is doing it, but considering the work it would take I doubt ATI would even bother trying to implement it on the 4000 series. That's not even addressing the fact that a software implementation would be terribly inefficient. If you want a large screen to game in, I would suggest just getting a 1080p Plasma TV to use as your monitor ^_^.