There is no corn-free meal replacement that I know of for sale in Canada, and I have been looking for years. If you find one, let me know!
For instance, Vega, the first vegan meal replacement formula on the market, is supposedly free from corn. However, all three flavour formulations contain small amounts of sugars (maltodextrin, dextrose, etc., and xanthan gum) from a source likely to contain corn. I found this out by emailing and phoning the company on January 9th and 10th, 2008.
Better to check with the company about ingredients and be safe, rather than sorry.