Wait a minute... wasn't it also GameStop who claimed a Nov 1, 2010 release date some months ago? (I'm pretty sure that there was a thread about that here on ZD, but I'm too lazy right now to look it up). I've said it a couple times during the past year and I'll say it again: I still believe in a Feb 21 release date (25th birthday). But looking back at what they did with Twilight Princess, it could be delayed until the release of the "Wii 2" (which I think could be anywhere between late 2011 and late 2012).
And I also have to say a word to all those who think that if they release it soon, it will be "rushed" or "unfinished" etc: Come on, 4 and a half years should really be more than enough for a whole developer team to produce a game. And personally I think that sometimes the first thought is the right thought and by "polishing" too much one can also screw up things. Majora's Mask was made in less than 2 years but in my opinion it was the best 3D Zelda game yet with innovative gameplay elements, deep story, excellent graphics and music plus it had some good challenge. There's a reason why it won the "Game of the Decade" contest at GameFAQs even though it's 10 years old and competed with ultra-modern high-gfx games like the CoD series, WoW, AC etc. and of course the newer Zelda games.
Now look at Twilight Princess: It took them over 4 years to complete and while I think it's still a very good game, I also think that they overdid it with "polishing/finalizing" etc. because in the end it was way too easy and linear. Maybe they first wanted it to be more challenging (Beta Gohma >>> actual TP Gohma) but after thinking and polishing too long, they made it ridiculously easy.
What I'm trying to say is: A longer (or artificially prolonged, as I like to call it) development time doesn't necessarily make a better game (it can make a better game though! An example for a game that was really obviously rushed and therefore had a lot of bugs was the original Final Fantasy II for Famicom, which had a development time of less than a year).
I'm going to wait until the release of the "Wii 2" anyway before getting the game (don't have a Wii), so it won't bother me too much if they delay it again.
And, correct me if I'm wrong, I don't think that there was a playable demo of TP at E3 2005 but there was one of SS at E3 2010 and at least to me it looked like the game was finished ~90% back then, so besides sales strategies ("Wii 2", 3DS...) there is no reason why the game should take another year to be completed.