Folks -- I don't think this issue is with Facebook, I think there seems to be an intermittent bug with the Facebook app on the Droid.

Here's the workaround for when this is happening:
In the news feed (or wherever else...) long press on the item/friend/etc. to get a popup menu, then touch "View profile". It should work to view your friend's wall as it did before.

EDIT:
This doesn't repair the issue so you can single click in the feed, it just allows you to see the friend's wall in the app.