I don't think there is any ONE thing that causes the wobble. I've done some internet searching and have found many Scientific papers on the subject. Here are a few:
I found that once I decreased the pre-load in the rear and increased the front that my "Wobble" decreased dramatically. But I also have 2000miles on my 908s, so that could be a factor.
I want adjust the forks. Because one of the papers I read (I forgot which) said that an increase in fork length decreased wobble.