Severe weather this year has been rather noteworthy at times -- June's derecho, remnants of Isaac bringing a couple of tornadoes last week, to name two events. However, in terms of total numbers of events, it hasn't been significantly different from last year.
the West is a lot less "severe" in terms of weather compared to east of the Rocky Mountains. The combination of topography being less favorable for severe weather development, atmospheric patterns historically (a lack of Gulf of Mexico moisture), and more sparsely populated areas help limit the reports...although the latter is not a much inhibitor in the data...there simply is not as much severe weather from a wind or hail standpoint from the Rockies on west.
All of the data in this post comes from the Storm Prediction Center, which has a great database of severe weather reports that go back several years. The database includes preliminary information so it's a bit more of an apples-to-apples comparison of years (which is how our comparison is year-to-year). The numbers this year suggest that it's been a relatively active year but not one that's terribly skewed out of proportion to past years. With the Fall severe season providing a secondary spike historically, we may end up with these numbers bumping a bit higher before year's end.