I have found the PreK Round 2 Directory to be a useful resource when you are assessing your chances of gaining entry to a public prek program. The DOE has removed their file from the website, so I will link to it here. It is a bit large so it may take a minute to download.
So what are you looking at? This is just for research at this point. These numbers don't represent current seats available. In the "applicants" column they are showing you the numbers of ANYONE who ranked the school on their application that year; they may be out of district or out of borough and they are definitely not "first choice" numbers. Some of the numbers may be daunting, don't freak out. The "seats" column shows the numbers of seats available in the first round. What has happened in the first round is that the computer has placed the exact number of seats and no more (no waitlist). Because the list comes out on May 31, some families who have been offered seats have paid their deposits and decided to stay in their current private nursery schools, some families have gotten grossed out with the whole thing and moved to Jersey. The number of seats that haven't been scooped up by those families will be up for grabs in the second round, even in highly sought after schools. There will be a second lottery and the same "priorities" apply; siblings in the school first, then inzone families, then out of zone/in district, etc.
The first round prek directories for 2011/12 will not come out until Jan. (on the DOE's website and hard copies in the schools) and the deadline for the application has previously been in early March. You can start calling schools and checking their websites for tours now.
The DOE has announced the kindergarten application timeline but they only have it listed under special needs for some unknown reason. I suspect that these dates will remain true for all students:
Kindergarten application period: Jan. 10, 2011 - March 4, 2011
Families notified of assignment offers: March 21, 2011 - March 25, 2011
Offer acceptance period: March 28, 2011 - April 15, 2011