Come on people, before you say it's anything but Kid Icarus read Naz's post :P.
I'll add on to Naz's points with a few. It's not going to be anything like Wave Race, Earthbound, Mother, Ogre Battle, Star Tropics, Eternal Darkness, Star Fox, etc. Bozon noted that so far when he's heard about a secret game he can't tell anyone about he has no problem not telling people. This is the first secret game that he's dying to tell other people about.
Also, usually with these secret games Bozon will either say what the game is on the podcast and it will be bleeped or Matt will give an obvious hint. Neither happened this time. I would take from that that this game must be something huge and sorry to the fans of the games listed above but a new version coming to the Wii wouldn't be earth shattering like this apparently is. This seems to be on the scale of Zelda 64 or Metroid Prime.
I'm not sure if they specified that it was a Nintendo game so there may be some 3rd party franchies to toss around as well. However, if it is a Nintendo game just go and look at the franchises Nintendo made in the NES/SNES/GB days and see which haven't been made for a while. http://en.wikipedia.org/wiki/List_of_video_games_published_by_Nintendo
The only NES games on that list I see are:
Urban Champion
Clu Clu Land
Balloon Fight
Ice Climber
Wrecking Crew
Kid Icarus
Gumshoe
PunchOut
Slalom
RC Pro AM (as a side note, awesome game)
Anticipation
To the Earth
Cobra Triangle
Faxanadu (second side note awesome game)
Star Tropics
Snake Rattle and Roll
Joy Mech Fight
Wario's Woods
So looking at that list the only possible game that gamers have wanted to get a sequel for forever for is Kid Icarus. Punch Out, RC Pro AM, and Faxanadu were great games that I think should get a sequel but I don't think many others have been calling for it.
My last point is that we should be excited about the people behind the game. Given that we can be pretty certain this involves transforming a 2D franchise into a 3D one that sort of points to the studio. Name a studio not called Retro (well, or Nintendo) who has garnared widespread accolades for successfully turning a 2D side scrolling game into a modern 3D one. I can't either. What better game to set Retro to work on than Metroid's sister franchise?
Edit: The only other franchise I can really think of that could qualify is Pilotwings. We haven't had a Pilotwings game in 11 years, which if the comment that you had to be over 12 to remember the game is true and not facetious then Pilotwings could be included. Some, especially Matt and Bozon (and me), were really psyched about the potential of a Pilotwings game when the Wii came out. Although I don't know if it has had many gamers demanding a sequal, it's doesn't seem very big, and I'm not sure what studio would be making it or why we would be excited about them making it. That being said, if Matt and Bozon are acting in a bubble (let's not forget they really pushed Z&W and Eternal Darkness so they don't fit the profile of most gamers) then I suppose it may be Pilotwings but my money is still on Pit.
