dvlenk6: excellent example.
 
I've always read that Higher DPI is better for images that will be printed.
 
100-150 DPI are supposed to be the ideal resolution for BubbleJet / Injkjet Printing anything higher is good for Professional printers.

However recently I've gotten a bit confused about the entire matter.

5 MegaPixel Cameras produce 2000+ x 2000+ Images at 72 DPI.   I've always been told 72DPI is the desired resolution for Screen display as the file size is smaller and you dont need the unneeded resolution if you are not going to print them.
 
However when these photos are printed at a Digital Printing services like at Wal*Mart the 4x6 Photos are pretty sharp and hard to tell that they came from a Digital Camera.

Higher DPI settings on a Digital Camera would probably introduce new problems. i.e. Higher Processor and Larger Memory would be required to handle the larger file sizes.