Since last we had a thread on this topic, things have heated up. In the one corner, Nikon has come out blazing with two new cameras, the D3 and the D300. The former is Nikon's first "full frame" digital camera, 12 megapixels, 9 frames per second (or 11/sec when cropped), and allegedly usable at a maximum ISO 25,600. Also included are a shiny new autofocus system with 51 sensors, and a "live view" mode that allows you to watch on the rear screen (just like a pocket camera) and with autofocus still enabled. All yours for $5000. The D300 is a souped up version of the D200. It has 12 megapixels, but in a 1.5x crop. It's allegedly usable at a still impressive ISO 6400 and cranks at 6 frames/sec (up to 8 with the external battery pack). It's got the same shiny new autofocus and such, and also had an anti-dust feature. All for $1800. Both cameras should be out by November.
On the Canon side, we've got the new barn-storming 1Ds-Mark III, full framed, 20 megapixels, and five frames per second. You get live view, but no autofocus while in that mode. Still, 20 megapixels. All for $8000. Such a bargain. Canon continues the 1D-Mark III, with a 1.3x crop, 10 megapixels, and 10 frames per second, for $4500 (the logical competitor to Nikon's new D3). Canon also just announced the 40D, which slots in pretty close to the Nikon D200/D300. 10.5 megapixels. 6.5 frames per second. Better weather sealing. Dust reduction, fancy new autofucus, etc. Basically, a very close competitor of the Nikon D200/D300 for $1300 (for contrast, the Nikon D200 is currently selling $1500). The IDs-Mark III is due in Demember and the 40D in September.
And, on top of all that, Sony has announced a 12 megapixel sensor (1.5x crop) that can go 10fps. This may or may not be the same as the sensor in the D300. Presumably, this will show up in some future Sony (nee Konica-Minolta) bodies, among other places.
No matter how you slice it, these new cameras are fantastically improved over earlier generations. Nikon is (finally) making a serious run at Canon for the photojournalist market. That, alone, will be fascinating to watch. Also exciting, the new D300 has specs that completely eclipse Nikon's earlier D2xs, for less than half of its price. That's trickle-down in action. I'm just hoping I can pick up a used 17-55mm DX lens cheap from the pros upgrading to the D3 (where you wouldn't want a DX lens like that). Likewise, it seems like I'll be finally retiring my Nikon D70 after three years of faithful service. The D300 improved on every one of the things I'd found lacking in my D70...