Here’s a little Facebook tip that might be preventing you from seeing updates from some of your friends.
Login and then click the “Live Feed” link on your wall. Then scroll to the bottom of the wall and click the “Edit Options” link at the bottom corner. Again, make sure you are on the “Live Wall.”
A box will open up and in the lower left corner you’ll see “Number of Friends.” The standard number is 250 (I think), so what that means is if you have 500 friends (for example) you probably aren’t seeing updates from a good chunk of your friends.
When I discovered this and upped my number I instantly started seeing updates from friends that I typically didn’t see. It was a very pleasant change. Check it out and see if you have the same experience.