Dye-based inks are far more prone to fading than pigment based inks. Epson makes a range of pigment based inks that has a wide gamut of colours (the ultrachrome inks) and a long lifetime, up to 70 years if handled properly, ie under glass to avoid UV exposure etc etc. This is the same life expectancy as many of the traditional silver halide processes.
Canon's PIXMA i4000 looks like a very sweet little printer. It's almost throwaway cheap (like $149 at my local OfficeMax), has separate removable ink tanks, and uses pigment based inks. It only does four colours, so the gamut is a bit less than the 6/7/8 colour printers (like the expensive Epsons and Canon's i8500 printer), but it is hard to argue with the price.
If you have your prints made at your local WalMart on their Aladdin machine, you'll get a silver-halide based print that has the same longevity as traditional film based prints.