Where can you find it and how much does it cost? How does it work?

According to the Mayo Clinic, the pill, called Plan B, is available through the pharmacy, without a prescription, to women over 18. If the woman is under 18, a doctor's prescription is needed. The Mayo Clinic article gives various information, including how the pill works:
Morning-after pill: Emergency birth control - MayoClinic.com (http://www.mayoclinic.com/health/morning-after-pill/AN00592)

The following site gives you information on locations where you can find Plan B:
Emergency Contraception (http://ec.princeton.edu/)

One more article about the pill:
Plan B Consumer Home Page (http://www.go2planb.com/ForConsumers/Index.aspx)

When in doubt, call your pharmacy and ask. They can tell you the updated laws, the availabilty and cost.

Here are also websites for the abortion pill, RU-486:
RU486Facts.org - Medical Information about RU-486 (Mifepristone) (http://www.ru486facts.org/)
Abortion Clinics & Abortion Pill Providers (http://www.abortionclinic.org/)

How does it work?

It is loaded with high level hormones that bring on a period within 12-24 hours, thereby removing the endometrium (uterine lining) as well as any potentially implanted embryo. Therefore removing the potential "pregnancy".

Cheers

I have taking the plan B pill recently I got it at wal-mart pharmacy for 45.00 I don't encourage girls to take it on a regular basis but I understand when a slip up happens my soon to b husband went and got it for me cause we had a slip up and we didn't want me getting prgnant before our wedding day. It didn't really affect my cycle or nything it just came a few days earlier than usual then everything was back to normal. Its 2 very small pill one you take right away the other 12 hrs later.

If you also have a free clinic where you live or a Planned Parenthood... you can get the plan B for free... that's what I did!