I'm in my niece's wedding this Fri (see last week's post on me letting her use my house for the rehearsal dinner). Anyway, she apparently thinks that Facebook is the best way to communicate with people. It's really not. There are a few people in her wedding party, and older relatives like my mom, who don't go on Facebook at all and are completely in the dark. She posted the rehearsal dinner invite and the day before and day of itineraries all on a Facebook group that she set up for the wedding. No paper invites, and I don't think any emails (at least the people I've talked to in the WP haven't seen anything).
I've had her groomsmen (one is my FI and another is a good friend of mine), her usher (my nephew), her photo booth people (also friends of mine) and her grandma all ask me for detais because they have no clue where they are supposed to be and when.
Facebook is great for catching up with old friends, networking, etc, but isn't really the place to communicate the details of the most important day of your life. Paper may be old-fashioned, but it's an actual physical thing that people can use and look at.