OK, OK, serious thoughts on the subject.
Canada has for decades pursued a policy of official multiculturalism. Does it work? Is it better than the melting pot apporach? Worse? The same?
Like most serious things in life, in moderation and applied with common-sense, there is no doubt that, at least in Canada, it has been a successful policy for the most part over the past 40 years or so. In Toronto we have perhaps the most cosmopolitan city in the world. We have a tremendous mosaic of ethnic neighbourhoods which are, for the most part, accessible to other cultures. People in general seem intrested in joining in each other's celebration of their heritage. And we all (in general) seem to get along in the workplace, at school and of course at Blue Jays and TFC games.
By de-mystifying each other's cultures, we remove the 2 main reasons for prejudice: fear and ignorance. It does seem to work.
But there are cracks in the facade. Specifically since 9/11, a degree of suspicion and mistrust has grown on multiple facets of the mosaic. It's the moderation thing: when some members of a specific culture (whichever one) turn inward and isolate themselves from society at large, then even if their motives are benign we witness the return of ignorance and fear, and hence prejudice and conflict.
My conclusion, having lived in Canada for 20 years and also travelled quite widely in the US, Europe and South Africa, is that yes, multi-culturalsim does work if, and only if, it is introduced into a free society that is already somewhat tolerant, and in a way that strongly encourages groups to share their culture with the community at large.