In Bruce Fraser's book on Photoshop sharpening techniques he makes an interesting claim. He restates the common recommendation of 300dpi for general printing with an Epson inkjet, dropping to 240 dpi for very large prints. But he then goes on to say that for small prints "there's a small but useful advantage to be gained from printing at 480dpi".
I've previously experimented with my Epson R2400 and found very little if any difference between 300dpi and 360dpi (occasionally I'll have a subject with a faint and localised moire effect at 300 dpi which is gone at 360 dpi), but there's virtually no resolution difference that I can see. Consequently I've never printed at higher than 360 dpi and was sceptical that there'd be anything more at 480dpi.
However, when I ran some prints at 480dpi it's exactly as Bruce described, a "small but useful advanatage". It's only noticeable under specific conditions; definitely no uprezzing, an accurately adjusted printer, moderate and appropriate sharpening, gloss or semi gloss papers, detail rich subjects captured with the highest technical standards, and close scrutiny in very good viewing light.
I've got mixed views on this result. Personally I'm not a great supporter of the current trend towards bigger and bigger prints, so I'm pleased with the idea of the digital equivilant to an intimate and precious silver contact print. And a better print is always a good thing. But on the other hand it's sobering that 480 dpi means a 22Mp digital back is only capable of an 11"x8.5" print!
