Yesterday I was surprised to discover that, in my latest Ubuntu 9.04 system, each user's home directory was readable to all other users (ie: permissions "drwxr-xr-x"). I seem to remember that this was not so in Ubuntu 8.10 and earlier, so I can only assume that this is a result of the latest upgrade. Whether it was intentional or not, it is not what I want, so I fixed it by starting up a terminal console and entering:
sudo chmod o-rwx /home/*
Each user home directory now has permissions "drwxr-x---" and is only readable by that user.
[Edited 2012-11-15 to correct permissions.]