Since the topic is still new, let's debunk some shit off the bat:
1. Microphone in Wiimote.
No. If they are doing to need a mic, they'll make a headset, and make it compatible with both the DS and the Wii, and possibly future iterations of portable and console systems. In fact, one was being made at some point, but I don't know what happened to it.
2. Wacky neato thing like VR/projection.
Absolutely not. There's nothing that tells us this is possible at this moment. We've had enough dissent from people whining about how they are going to knock over their Faberge eggs with their flabby arms, so I doubt we'll see something added to the Wii's interface beyond the controller.
3. Powerful as the 360/PS3.
Not possible. The machine is too small to provide sufficient cooling to pull this off.
4. DVD movie playback is included.
We all know how penny-pinching Nintendo is. Not happnin'.
5. Physics chip in the Wii.
See 3 and 4.
6. Mario Galaxy and/or some other wanted title is a launch title.
Don't set yourself up like that.
7. There's a Wii SP or such that will have DVD playback or something.
Wtf. Don't tell me that after I've locked in on a Wii. 'Cuz you know how big of a consumer whore I am, Nintendo, and you damn well know if I could have gotten a Q, I would have. So don't piss on my face by offering me something badass in light of the first thing I already f*cking bought.
You have to start thinking at this point about "what does Nintendo gain by keeping something secret at this point?" We're so late in the game that there is literally almost nothing that could be so awesome that either they don't want MS/Sony to steal it, OR they have an advantage by not telling consumers before launch. I can't think of many things that satisfy one or both of these criteria adequately. You could have some nice fancy tech in there no one knows about, but we'd need to see it now in order for it to make an impact.
For example, it can't be "the graphics are being held back," because there's no damn reason for that. Same with VR/headset/etc. You're trying to build hype now, and if we're beyond the point of no return (which we are), you gain almost nothing in hiding stuff.
At best - assuming this is true - it's going to be much less grandiose that people will speculate. So it's going to be a Wii Channel or Wii Play bundled or something with the online component. It could be something about DS Connectivity as well.
I personally don't even think this rumor is gonna happen.