depends on the printer and whether it has the ability to print a vector file directly or whether it is converted to bitmap data anyway. either way you are limited by the DPI of the physical printer itself. you can have a 10,000 DPI graphic... doesn't make a lick of difference if the printer is 90dpi.
The printer I use (i say printer as a print company not a physical printer) wants data in vector format. what they do to it there is beyond me. But I make the graphic, give them the AI file and tell them I want it X by Y in size. (i mean i make it in that size, but i also specify it to them so there is no mess ups) Because it's vector, it's infinitely scaleable without degradation whether it be 20 inches or 200. I wouldn't export the file as a PNG or anything and submit that to them because then the vector graphics are converted to a raster graphic like a bitmap and if i didn't match the capabilities of their printer exactly, i'd end up with nasty looking prints or mismatched sizing.