Craig Meddaugh , Feb 23, 2010; 03:14 a.m.
None of the Canon cameras are warrantied for water or environmental damage. None of the Canon cameras are tested to any of the international standards for weather resistance. Absent a warranty or testing to international standards, you can pretty much assume that these things should be treated with care.
In other words, no one (Canon included) knows exactly how weatherproof each model is, so when you play in the water and dust, you should probably use protection of some sort.