Update: It looks like they disabled the ability to check to see who defriended you on Monday. If you caught this post when I originally sent it on Saturday great, if not it's no biggie anyway. You can still follow the steps below to enable Facebook Timeline before they start to force it soon. At first glance, it's too different and I'm not a big fan.
I came across two articles over the weekend. One that said you can find out who unfriended you on Facebook using the new Facebook Timelines feature that will go live either Friday or Saturday this week and the other listed the steps required in order to get the option to enable Facebook Timeline NOW, ahead of the general public, which is required to find out who un-friended you. So click on the second link to enable it, then follow the steps in the first link to find out who un-friended you.
Shockingly, it appears no one unfriended me. To test it out I had my wifey unfriend me and then it did show that she had unfriended me, but no one else did, so it appears to be working. It's a bit confusing, but once you are setup with Facebook Timeline, on the right it lists months and years. Click on a year, like 2010 for example. Then you scroll down to where you see a 'Friends' heading and it should say something like you made 52 new friends in 2010. Click that link that shows the number of friends you made that year and then scroll through your friends and if any of them have an 'Add Friend' button, they are no longer your friend but they were before.
I'm guessing that feature may go away by the time it goes live to everyone, so if you want to try it out, do it now before that option goes away! That's just something interesting to try, but the bigger issue is how Facebook Timeline will COMPLETELY change the layout and function of Facebook. I think with so many changes over the past few weeks and now this entirely new look and feel, that they'll get a LOT of complaints and pushback and I'm guessing they'll delay the rollout or scale things back.
Enabling the ability to use Facebook Timelines as mentioned above does NOT require you to switch to that new layout permanently now in order to see who unfriended you. But if you would like to get started setting up your timeline now, you can. Might as well at least take a look so you'll know what everyone is talking about when they start complaining at the end of next week.
If you try it out, let me know what you find out and what you think of the new setup.