Earlier today I finished up the Meteor Login sample app using Github's API and decided to attempt the same with Facebook's LoginAPI. Meteor makes it so easy that I was able to replicate the same results in two hours. The reason that it even took that long was because I was not accessing the Meteor.user JSON correctly.
For the code go my github repo at: https://github.com/m2web/facebooklogin.
One thing to note is the setup of the Facebook Login App for testing at Meteor's default location of http://localhost:3000.
Of course, once you deploy the app, you will need to update the above settings to the correct domain and URL.