What you think doesn't matter. Think for the community, not about whether or not you actually like facebook, etc; Besides, the Glest Team did it. 
Please watch your tone a little. Saying things like "What you think doesn't matter" is insulting and thus counter productive (meaning: it actually prevents it) in reaching an agreement.
New reply: Just because you don't want it doesn't mean we shouldn't do it. By taking advantage of social hubs, we attract more players, something the Glest community can always use. A Glest page already exists on facebook, set up by the very people who made Glest, showing they obviously can agree. These days, every major business, product, musician, movie, etc has its own facebook page, which not only works as free (!) publicy on one of the world's fastest growing sites, but allows players to show their support for the game (along with more publicy as joining the group may appear on the player's wall, etc) and give another method of communicating updates to the game, even to those who don't frequent the forums anymore).
Pros: Free advertisement on a very large site, another method of communication, welcome to the 21st century
Cons: None. Haters may hate, but you have no valid excuse.
