We were thinking about adding Omniture tracking to our Facebook fan page...But with the new Facebook Insights reporting released just a few days ago, I've found that it gives us about 90% of the data we need to measure the impact of our FB interactions (above and beyond simple "fan" or "like" growth). It gives specific information about the content that you post to the wall, as well as activity by FB page, demos, and some engagement metrics (e.g., daily active users and daily post feedback).
P.S. They're slowly rolling this out to all users, so this same report may not be available on the link that's traditionally on the left nav...so definitely go to the /insights page directly and login.
Yes, the updated FB Insights is a lot more intuitive and insightful than the legacy version. Plus it's free, unlike the expensive Omniture solution...Of course I'd be interested to know how well the GA FBML solution is working out for users...Have you heard from anyone directly? Aloha!