Honest question: does it really matter? If you're obliquely referencing the holiday season, I have to think that the number of people for whom giving this as a gift is a viable option is basically a rounding error in Apple's customer base. I could be wrong, though.
“Before the end of the year” is important in this case not for holiday sales, but for 2013 tax reasons. I doubt even seriously rich people would be buying this as a gift ;-)
Good question. They specifically listed Nov 1 for iPad but not so confident in the Mac Pro date, I guess.