Here's a thread ...
http://www.airlinepilotforums.com/fo...onversion.html
There's some discussion on Pprune as well, but you'll have to dig it out from several FAA/JAA threads.
The consensus, at least for FAA to Canada, is that the process is straightforward. Now that it's been going on for a few years there are some good written exam preps. Somebody on the AOPA forum did his in Vancouver and spoke well of the office. I'll do it myself eventually. One gotcha is that the agreement is for f/w certificates only, for some reason.