I think the worst thing that an amateur photographer can do is wait until some hoped-for new DX body shows up sometime in the future this year (Spring? Summer?), make the purchase and then end up leaving its inevitably superior resolution, high ISO performance, AF speed, etc., etc., in the camera bag because he hasn't had enough weekend shooting time with the thing to make him familiar and comfortable enough to justify making it his primary body for use on a long-planned and possibly not-repeatable photography trip.
On the other hand, buying the wonderful and notably superior D7000 right now gives a photographer lots and lots of time to experiment with the D7000, shoot some projects with it, absorb how his favorite lenses work with it, adjust his technique to include generally faster shutter speeds to ensure all those megapixels capture the sharpest possible images, and so on, and so on. A once-in-a lifetime trip to Iceland is not a trip to take with a relatively unfamiliar new camera. Quite the contrary, it's absolutely a trip to take with a camera the photographer knows thoroughly well.
Several others in this thread have mentioned something just as important. A shiny new advanced DX camera body model is just as likely to show up with early-adopter/early production run teething problems. Why take the chance?
The D7000 - given its superior imaging capabilities, all of the user knowledge about it available to be tapped here on Nikonians, all the guidebooks written about it, all the wonderful published images that have been made with it - is a top quality, 16mp bargain right now. So my advice it to buy it now, mount your favorite lens, and then shoot with it as much as possible between now and your departure date for Iceland. You won't be sorry. Against the exceedingly rare chance that your D7000 fails for any reason, you'll still have your equally familiar D90 as a backup. I think that's the best of all possibilities in your situation.