Has the dishwasher always done this? If not then it could be a drainage problem, you might also check to make sure the jets in the spayers aren't clogged.
If it has always done this, it might be a water issue, but the rinsing agent should have fixed that, what rinsing agent is for, it basically breaks down the surface tension of the water so it drains off before it can spot the dishes.
I'm guessing it is a jet problem, you might want to take a look there. If the pump at the very bottom of the dishwasher where the water is pumped from is full of crud, clean it out and run it empty, vinegar or lemon juice would be good, probably lemon juice is better since the chemistry would work better. Also if there is still a lot of water in the bottom the pump might be bad.
Good luck, if that doesn't help, let me know and we can try a couple other things.
DrB