I have seen this 3 week rumor going around photography forums as well. The stuff spreads like wild fire. The only verifiable information is that the current purchase would yield a supposed 3-4 weeks delivery; however, if you preordered and you have a ship date, then that is when it is suppose to ship.
Until they ship it, money taken or not, you can cancel. You choose what you want to do.
I myself am contemplating, if it is delayed again (and nothing in the world says they cannot delay shipping again) past the 19th, that either this will be the best built machine ever to come from Apple, or something is amiss with Apple themselves. I just don't know and speculation doesn't breed truth necessarily.
Cost to me on this laptop will be $2,900 with all the tax and extras I ordered.
I am thinking now that if I get a 2008 refurb model from Apple, I can have a warranty, Applecare, 4GB RAM, larger hard drive with the option to expand to SSD and still have money left over for probably a 24" ACD on the side, give or take a couple hundred.
I will make my decision in the next few days while Apple makes theirs.