Pete announced a couple years ago that he was leaving the forum to do other things, but it took him quite awhile to go. Being forum owner has certain responsibilities, and I think he wanted to be sure that moderators such as Solitaire and Michael Calkins had things under control.
It's understandable, given that the old forum ain't what it used to be -- sometimes with only one post every several days. In any case I'm sure we all miss his presence on a regular basis. I know I do. The only reason I still drop by every day is that unlike Pete, I don't have a life (well, a wife and son, anyway).