Hot on the heels of Canon's pre-announcement of its new, all-things-to-all-pros full frame 1DX, Nikon is scheduled to announce the D4 this Friday. Unsurprisingly, the rumoured specs are very close to the new Canon. If you're comparing to the D3(s), there's more of everything. More speed. More pixels. More high ISO capability. More video gubbins. You get the idea. (Inevitably, the spec-sheet doomsayers have already decided that there's not enough more-ness, but that's another story).
I'll have more to say when the launch is official and all the specs are confirmed. For now, though, I'll just point out that, barring surprise spec details that haven't been leaked, this is to all intents and purposes an incremental upgrade. Successive generations of Nikon's top pro dSLRs have, until now, offered substantive gains over their predecessors. Given the stellar and proven performance of the D3, though, the new model has its work cut out to persuade working pros to upgrade (and that's before we know the price. If Nikon matches Canon's new price point there'll be a lot more credit cards staying warmly nestled in wallets).
As for the rumoured D800 with 36mp... it occurs to me that many of its target buyers are likely to bolt it to a tripod, stop the lens down as far as it'll go and lose much of the extra detail advantage of all those pixels in diffraction (which may account for the rumoured anti-alias-less version). But who am I to argue? I'm sure it'll go down a storm.
Check back on Friday for more...