My favorite bit was that all the extras in the Mother's scene were actually members of the production staff on the show, (including a former co-worker of mine!), utilized to cut down on the possibility of the scene being leaked.
Indeed, they really went to a lot of effort to keep this scene a secret until broadcast. It's really renewed my interest in this show, like you, I say bring on Season 9!
ETA: I've been watching the last minute or so of the finale here,
probably more than is absolutely normal
but I can't help it. I'm filing the mother reveal in my mind as one of my favorite moments of television. I think in the future it will end up in one of those lists of "Best moments in Television ever" or some such.
Also, I love lurking on the IMDB for this show and watching all the Ted/Robin shippers dealing with this revelation.