Well one would think that it might take place after TP, judging by the artwork and stuff. But it was stated in an interview with Miyamoto that the game wold take place in an entirely different era than TP. So, apparently it won't be a sequel.
The reason I said that it might go before OoT is because based on interviews with the developers, OoT is the first story. Some people say that MC is the first now, though I haven't seen an actual interview, MC does make sense to be first since its so out of place. So, if MC is first, and the Master Sword is no where to be found, then OoT would be the next generational title, and the Master Sword is present, then there is a gap between those games where Nintendo could fit a story around the creation of the Master Sword. Since the girl in the pic looks like the Master Sword, and Link has no sword in the pic, to me it shows that she will become the Master Sword, and that Zelda Wii will detail these events of its creation. That is why it would go before OoT, because the MS is already created in that game.
tryin to put up a song for all u gamers: zelda medley mp3 file:///C:/Documents%20and%20Settings/Owner/My%20Documents/My%20Music/iTunes/iTunes%20Music/Unknown%20Artist/Unknown%20Album/Zelda%20Medley.mp3
tell me if it works, if any of u decise to download...