Most likely, of course Notch will probably include a few patches between now and then, however we won't be seeing any major additions in content until Halloween.
Notch is utilizing whatever time he can to minecraft, he is just choosing to hold onto content which is already developed until Halloween, thus releasing everything at the same time in a much larger update, rather than smaller ones. This update will undoubtedly create a lot of hype which will certainly get more players into the game, from a marketing standpoint this doesn't seem like such a bad idea.
Would you rather he spreads the content out over the course of a month, or release it all at once? Obviously everyone would have their own opinions.