Nikon today announced the replacement for the D80, which turns out to be the D90 model that I predicted late last year and gave (accurate) details on previously (which have been bouncing around the Web ever since, often without noting the source; not that I care about that from a ego standpoint, but the big problem with the Internet is attribution; it's hard to understand the validity of an assertion without knowing the source, especially when we get rumor sites quoting rumor sites). But that's not important right now...
Most people are going to want to know what's new, so here's the easy of way of understanding the D90: take a D80 body (exactly). To this replace the old LCD with a 3" 920k dot one (same as the D3, D300, D700). Next, add two buttons (INFO and LIVE VIEW). Finally, add a microphone and speaker as well as a GPS input port. That's basically the external differences.
Now, to the inside: swap in the D300's 12mp CMOS sensor (and all that implies vis-a-vis Picture Controls, ISO, sensor cleaning, etc.), update the metering to use the latest Scene Recognition System, then add a 24 fps, 720p HD video capability (via Live View). Sure, there are some additional menu bits and pieces (Auto D-Lighting, for example), and some minor spec changes (4.5 frames per second now), but there you have it: nothing that was broken was replaced, most of what people asked for and a few bonuses was added. Full specs are on my Current DSLR page.
Other than the video, there's nothing unexpected or even remotedly earth-shattering here. Just a solid, competent refresh of an important DSLR model. Price is US$1299 including the new lens. One tidbit: the Nikon GP-1 GPS unit that is optional for the D90 comes with a 10-pin connector adapter, too, so it can be used on the D300, D3, and D700, as well.
What new lens? The 18-105mm f/3.5-5.6G AF-S DX VR ED lens I also gave details on earlier this month, of course. Another competent upgrade (of the 18-70mm or 18-135mm, take your pick ;~).
Personally, I'm glad the D80 is gone. Early on it was plagued with the amp noise problem, the matrix metering was a bit loopy, and I always had hot pixel problems with noise (compared to my other Nikon DSLRs). It just didn't seem quite good enough to sit at the top of the consumer lineup. The D90 looks to be a different story. If it has the image quality and metering of the D300 it's a winner right out of the box. The rest of the features are about right for the "just under US$999" market. But...