Joshua Jackson was on the Bonnie Hunt Show and the Jimmy Kimmel Live!, talking about Fringe, and his boyhood home (mostly about his boyhood home). One tidbit to come out of these interviews is that he referred to The Observer as September, confirming an early press release with the same name. This doesn't make the name canon in the show, but it is interesting that he would use that name. One explanation is that September could be the internal code name for The Observer.