Having the monitor calibrated only allows you to accuratly post process your photo's using Photoshop or other software. Without having a calibrated monitor you do not know how true the colors on the monitor are. It has nothing to do with the output of the photo. That is when you need to also have the printer profiled. If all is profiled correctly then your print should match you monitor.
Its very difficult (at least for me) to get everything matching. I have a Gretag Macbeth eyeone display to calibrate my monitor. I only have Profile Prism to profile my printer (it uses a scanner to compare a known good color chart with a printed color chart so it can make neccessary adjustments and produce a printer profile), scanner based profile software is not as good as hardware based systems but they cost a lot less. It does good, but I still can not get perfect match between monitor and printer. Profile Prism helped alot when I started using 3rd party inks and papers. Using 3rd party papers and OEM paper profiles normally does not produce good colors.
Its alot of work to start but once everything is calibrated/profiled properly what you see on your monitor is what you see in print.
Now to your question, if the printing is done by others and it is properly profiled then all should be good. I do not think most quick labs (Kinko's, Ritz camera, etc) have properly profiled machines but I could be wrong.
If your monitor is calibrated then you would know by comparing prints between print shops which one produces better matching prints to your monitor and use them.
Until you posted, I wasn't aware of hardware monitor calibration. I've had a look into it, but I do wonder how worthwhile it is if prints will be done by a shop that may not have calibrated their printing. If I were doing my own printing, and I had the budget, then I'd calibrate both monitor and printer. Unfortunately I don't have the budget for it right now.
Is the difference worthwhile if printing is done by others?
Now if I find the local shop is calibrated, things might look different ...