Mark, if you look at the white paper by Karl Lang on the Adobe site, the best photographic or inkjet prints can have a CR of 275:1, but more typically 250:1. Of course, matt papers will have a lower DMax. My post was more in the order of a thought experiment and I haven't done such a calibration as I can not adjust the black point of my monitor. I would think that a monitor that displays an accurate rendering of the image at a CR of 288:1 would be adequate for soft proofing, but I would like to hear from Ethan Hansen or others who have actual experience in this area. Until someone convinces me otherwise, I think that a high CR is an advantage for a monitor.
Print contrast ratios depend on the ink set, printer (and driver), and paper used. Typical values for pigment ink printers range from 200:1 for high gloss stocks to 150:1 for lustre, semi-gloss, and satin, down to 40:1 and below for fine art papers. A few specialized stocks - usually polyester surfaces made for point-of-sale displays - can hit 400:1 or above. Dye ink printers achieve slightly higher DMax and, therefore, print contrast values than do pigment inks.
Silver-halide printers offer print contrast ranging between ~100:1 to 50:1 on standard surfaces depending on how much of the manufacturer's color
management software is enabled. Specialized papers such as metallic stocks are usually 40:1 or below because of the less-than-white paper surface.
In actual use, I have not found the need to reduce monitor contrast in the interest of print matching unless working with prints made on very low contrast paper (examples below). Instead, use Photoshop's soft proofing tools and train your eyes to interpret what they show. Simulate Black Ink helps determine if your shadow details wil show up in print. If not, adjust. The Paper Color simulation does the same for highlights.
As Andrew mentioned above, the simulations are not exact. Your eyes "white balance" themselves to the brightest element in your central field of view. These include palettes, docks, taskbars, menus, or other UI elements unless you view the image in full screen mode or use a multiple monitor setup. Without distractions, the matching between print and screen can be very good. Do not make major tonal adjustments to the image with the simulation enabled until you have the chance to compare a variety of prints to what Photoshop displays. There is no point in trying to edit out a simulation artifact.
If, however, you are printing to a comparatively low contrast surface, reducing your monitor contrast can assist in previewing what you will see in print. You definitely do not want to match the print contrast. Doing so will make your monitor impossible to work on. When using a paper with maximum contrast in the 40:1 range (Epson's Hot and Cold press fine art papers, most satin or glossy canvases, Hahnemuhle Photo Rags or Bamboo, etc.) reducing your monitor contrast to 150:1 to 200:1 is useful. Standard Matte papers or matte canvases (CR of 30-35:1) the lower end of the range is more useful. For jobs destined for newsprint (CR of 6:1 if you're lucky), I'll go to a monitor CR of 100:1. Lower and you simply can not see enough to work. Don't do this on a laptop - even the best screens pose enough problems already.
What printer you use is also a factor. For example, Epson's desktop printers (e.g. 2400, 2880) still do not use the same quality ink linearization and limiting algorithms as do their wide format brethren. Our data, Epson's canned profiles, and even Andrew & Co's PixelGenius Exhibition Fiber profiles all show the desktop models producing ~20% lower print contrast on a given paper than do the wide format printers. A quick comparison of grayscale step wedges shows why. Poor linearization on the desktop printers, decent to very good linearization with the wide formats.
Semi-related note to Andrew: Somebody goofed with the PixelGenius profile labeling. The 7800 and 9800 profiles are for the same printer and the 7880 and 9880 profiles are identical as well. The other profiles all look reasonable.