I have been doing a little research lately and came across two interesting sites for Moms in Montreal:
Wee Wiggles allows moms to meet up and chat (with or without their kids, I believe). It seems primarily to be based on the west side of Montreal.
Momtreal.ca has some good links for moms in Montreal, including stores, resources and activities.
Ecochick.ca is written by a woman who reviews eco-friendly products in Canada.