L.S.
as someone has already said ... try google search, look through yahoo groups, meetup.com and matchingmoms
Then if you don't find anything, just make up some fliers saying something like you've just started a playgroup in the area and have people contact you if interested. This is what I did a couple years back and just passed them out in my neighborhod, we now have been going for almost 2 years and have a great time ;)
Good Luck with it.