Just speculation here folks, but what do you think is the real reason behind the delay of Portal 2? I get the vague feeling that they are adding some (potentially dangerous) mechanic to the game, which is obviously a big deal. What about you folks out there, are we gunna have rocket jumping in Portal 2, or was there just a fire in the Valve office?

If Valve ever released a game on time it would cause a rip in the Space-time continuum  

Really, when Valve sets a release date it's usually actually a while after. Though Left4Dead2 wasn't all that late... :s

They just like toying with my emotions, and I fall for it every time.

It's really hard to read what's coming out of valve at the moment. First it's "Yo come see Portal 2", then "Ooops no Portal 2 but a surprise", then "The surprise is Portal 2 related!"
 
I know Valve delay games all the time, but announcing a Portal 2 event, cancelling it for "something else", then releasing another press release to quell the speculation suggests they misjudged something pretty seriously. 
 
Either that or this is all part of some grand plan to confuse the public. Duke Nukem Forever exclusively on Steam. Calling it now.

Its valve

" Really, when Valve sets a release date it's usually actually a while after. Though Left4Dead2 wasn't all that late... :s "

IMO they can take all the time they need, I trust they're not dumb enough to break it with some crazy new mechanic, but are instead possibly fleshing out the game to make it longer, or adding challenge levels or the like, and possibly they need to port it to consoles.