Here is a bunch of great info about weaning from La Leche League:
http://www.llli.org/NB/NBweaning.html
and extended breastfeeding:
http://www.llli.org/NB/NBextended.html
and below is the page where you can find a La Leche League leader or group near you. I called them on the weekend to ask a question, and even on the weekend, during the summer, the leader called me back within about 15 minutes and talked to me for over an hour... very helpful! Here's the page:
http://www.llli.org/Webindex.html