Here's what I understand from my research
Montreal is the second largest city in Canada after Toronto but also home to more MBA students (read HEC, McGill, Concordia etc.). The job market in Montreal tends to be divisive in the sense that you'd have to be truly bilingual for certain jobs - that essentially splits job seekers in two - those that are bilingual and those that are not.
For those that are not bilingual - you'd probably be better off in expanding your job search outside of Montreal - Toronto, Calgary, Vancouver or even the US. You still have a good chance of landing jobs in Montreal - you just have to work that much harder, network that much better.
If you are interested in Marketing related jobs in Montreal post your MBA - you better well be bilingual.
Just my 2 cents...