As a great fan of this lens, I recommend it highly and have used it in light rainy situations, BUT I try to protect it, in such situations, by placing a piece of "Saran Wrap" over the lens barrel. Camera bodies and lenses were not built to withstand heavy and/or sustained downpours.

Hurbee 04/16/11

Absolutely not. I have has terrible problems with this lens even in the driest conditions. I would certainly not recommend this lens in wet weather. It will fail on you as it is extremely cheaply made.

No it is not! Do not use it in very dusty environments. It's OK in rain provided you keep it dry or at least wipe the rain off before zooming it to the 18mm end. I got dust in my old version in the Sahara but then the sand there is so fine it gets into everything. It didn't cause any problems though with image quality so not much got in. If you are shooting in the rain then the biggest problem is keeping the lens raindrop free. Try using a lens hood as a rain shield and a plastic bag over the lens itself will keep the lens dry. It really isn't a problem. I use my D90 in the rain fairly often but not heavy rain because you can't keep the lens dry. An umbrella helps a lot in the rain.

BTW the D7000 is a wonderful camera.

I have used my 18-200 in all kinds of weather with great results. Had one on a D-200 for almost 5 years and never had to clean the interior or the sensor of the camera

No its not weather sealed.