According to Dave Kerpen, Facebook has added SMS to their fan pages. The new feature lets anyone fan a page by texting “fan [page name]” to FBOOK (32665).

So far the rollout is limited and appears to only be for Fanning a page. I have no idea how Facebook determines who’s profile the text is from, other than checking against your listed phone number. I texted the service myself and got “access denied” in response.