It is important to appreciate, that D800 is capable of producing superb images. Undoubtedly they are or will be cameras that can do some things better. For most of us, this means little because:
1) It takes considerable expertise to get the most out of a camera of this caliber and complexity on a technical side of things. I suspect few of us are there yet.
2) Technical quality is just one of many factors that make out a great photo and provided that some more or less minimal technical quality standards are met, other factors like creativity, composition and post-processing skills probably contribute a great deal more to the success of the photo than an incremental improvement in technical quality.
3) Despite what I said above, there are special issues and circumstances when a great camera may make it possible to get a photo that would be hard or (for all practical purposes) nearly impossible to get with lesser cameras. Better viewfinder, better controls, better (brighter) LCD, better sensor, better/faster processor/focusing/exposure can make a difference in some circumstances or can make photography easier and more convenient. Overall however, I think that most of us would get greater bang for a buck by learning to post-process better or by improving composition and especially by going beyond cliche and trying for something creative. I think that if this is not your real goal, a good quality cell phone camera is all you really need. Forget about some relatively rare events (for most types of photos) where in expert hands Hassellblad could offer noticeable improvements over D800
Personally, I'm interested in seeing what 24Mpx can do. I assume that the D3200, the entry-level Nikon, is going to be incorporating the same sensor as the flagship Sony A77 and NEX7, which is an excellent chip. The DX (1.5x crop) format is half the area of the FX (1x, aka Full Frame / 135 format), so the next step is to imagine what a 48Mpx FX sensor would be like with the best sensor tech behind it… hello, D4x?
If there's one thing that Nikon has proven, it's that they're happy to undercut their own products if they're caught in the middle of the upgrade cycle. (D3, D700, D3s; D300s, D7000; D5000, D3100 / D5100, D3200; D3x, D800, _____.) They've certainly been in an aggressive mood lately, so I'm very interested to see where this one-company technology war will end up.