The 'enlisted' thing seems to refer to signing up for something, seeing as people are using it as a verb.
However, not having found any clues, I don't know what it's all about. If I were to guess, I'd say it's either a promotional contest, or some other thing where the people who "enlisted" get some form of special treatment (as a reward for following along with the promotional clues all the way to the end).
I wish I would have had the time to follow along with this little promotional thing...if it weren't exam time, I'd be all over the hunt for clues and whatnot.
Oh well, looks like I'll just have to wait for the announcement tonight. I just hope I'm not missing out on anything by not being 'enlisted'.