There's a good amount of evidence that jumper's knee, which is often called patellar tendonitis, is actually a condition called tendonosis which isn't as much a factor of inflammation as it's a gradual breakdown of callogen (sp?) in the tissue. Rest and a gradual return to exercise that focuses on eccentrics seems to be the ticket. Ice, ibuprofen, stretching and soft-tissue work can do something in the interim. I've been struggling with this for a number of months and it's a HUGE nuisance. Rest when you can, try to sleep a LOT and put ice on it every time you turn around. That will make it bearable.
A test you can do to find if it's an itis or osis is to rest ice and take ibuprofen consitently. If it's inflammation-related it should clear up in a week or so. For me, that hasn't happened, so I know there's a problem with actual necrosis of the tendonous tissue...ice and pain-killers dull it enough to continue training, which is a necessity at the moment. Good luck!
Here's a couple of links from various forums, etc. that I've found in my search for answers to this: