No, all current Nvidia Geforce cards only support two monitors. Even in Windows.
For three monitors you either need two cards or a different brand that will support all three at once (ATI/AMD have some that do lots of screens but I'm not sure how well supported this is in Linux).
Edit: If you're determined to stick with one Nvidia card, you can get a Matrox DualHead2Go which is a box that you plug two monitors into and then plug that box into one of the outputs on the video card. It makes the video card think that those two monitors are just one screen. The downside is it's not cheap (over £100) and it also enforces some refresh/resolution limits.
They also do a TripleHead2Go (three monitors into one port) and this costs twice as much. But that does mean you could have 6 monitors coming off one Nvidia card which would be pretty epic (assuming it didn't crumble into dust trying to render that much at once).