The Canon L lenses are supposed to be weather proof just like the 7D. It's supposed to create a seal where water cannot get in.
Those Canon lenses you linked awhile ago were very nice sounding lenses. Eventually I'd like to get at least one of those, but I'm not anywhere near the proficiency level to warrant spending $1,000 for a lens. However I do need a telephoto lens and was thinking of getting the 75-300mm lens or possibly the 55-250mm from B & H, at least until I get 'photo skillz'.