The D7000 is technically an all-around better camera than the D300/D300s. Weather sealing in the D7000 is also quite good.
Lost in the feature-for-feature technical comparisons is the fact that the D300/D300s uses the original EXPEED processor. The D7000 uses the newer, faster, higher instruction capacity EXPEED 2 processor. That's a big difference AFAIC, and tilts every decision point in favor of the D7000. The combination of the EXPEED 2 processor and the new 16mp Nikon-designed/Sony-fabbed APS-C sensor is nothing short of astonishing, and produces the highest linear resolution of any sensor currently offered by Nikon or most other makers. All that EXPEED 2 processing power handling the amazingly responsive new sensor also means that autofocus/focus acquisition is likely better than anything else made by Nikon or Canon. Nikon has once again pushed the envelope here.
The EXPEED 2 contains more hardware instructions, more logic and does a measurably and noticeably better job of JPG processing out of the box. The D7000 saves images faster (JPG and NEF), responds to commands faster and can accept all current and planned SD cards in its extremely fast card slots. The dual SD card slots in the D7000 are a shooter's dream - use slot 2 for backup when the slot 1 card is full, or use it to automatically backup everything shot to slot 1, and so on. The dual SD slot setup and programming is a direct lift of the wonderful D3/D3s/D3x dual CF slot design.
While the D300/D300s was a superb, award winning design, Nikon has really hit the drawing boards hard to come up with the D7000 in the face of Canon's excellent new 7D. I think Nikon has scored a game winner with the D7000. Frankly, despite the fact I've been shooting a D700 for several years - and a D3s more recently - I'm getting ticked off at the superb quality of the D7000 images I'm getting out of such a tight, light, well-heeled package.
APS-C, here I come (again) for travel. That the D7000 is lighter and apparently almost as tough as the D300s is just one more bonus to add to the foregoing and to all the other pluses noted by other Nikonians in this thread.
I'm thoroughly impressed. Nikon knows how to design and build cameras. Now Nikon is also getting the hang of hi-def video too, so the D7000 is notably advanced over the D300s in that area as well.
There must be a downside, right? Well there is - sort of. After having the weight of a D700 to stabilize my shooting when using non-VR lenses (e.g., 24-70 f/2.8, 50mm f/1.4, etc.), using the D7000 and the eerily sharp little Nikkor 35mm f/1.8 DX is reminder of just how sloppy your handholding technique can get when you've come to rely on significantly heavier gear. However, it only took all of a couple of hours of general shooting for better technique to 'click in' after a bit of concentration. Now I'm getting exceedingly satisfying results out of the superb litte 35mm f/1.8 DX.