Countdown has its own page on the Symbian site (http://countdown.symbian.org/), so it's fair to say that this is something major. The Symbian Foundation now has a rolling cycle of product releases, so unless they're ready to jump the gun, it's not going to be code additions. The plan for many a year has always been slow and steady, with not too many surprises.
Knowing that, perhaps the significance isn't a countdown as such. By putting that reference at the start they could be putting in just a touch of distraction towards a time and away from the number? So how significant is 108? Could it be a number of new partners? That would have some literary significance as Homer, during his Odyssey, had 108 suitors coveting his wife. Who's coveting Symbian and their market at the moment?
More thoughts and ideas from Ewan in the full article.