The current 50L is one of my favorite lenses -- I love the look it gives. There is a video online somewhere in which photojournalist David Burnett comments about the special look of the 50L. I tried switching to Nikon, but there was too much Canon stuff that I missed, including the 50L.
I don't buy this theory of a corporate policy to wait for a competitor to make something better. Canon has been ahead of the competition with the 50L, 17TSE, 8-15 fisheye, 40 pancake, 85L, 24 with IS, 28 with IS, 35 with IS, etc. For quite a few years, Nikon offered nothing to match Canon's 24/1.4, 35/1.4 or 70-200/4 IS. Of course, Nikon has some lenses that Canon doesn't. Each company has its own priorities and its own timetable for updates. They're not just sitting back and waiting to see what the other guy will build.