As with the Leopard upgrade, if you upgrade to Snow Leopard you'll be surprised to find that once you are done, your /home directory will be empty and unusable. For most people this is no big deal. But if you are a developer and you like having your development machine machine your final production file system layout, you probably are using the /home directory.

There's already a tip that described how to fix this in Leopard: http://www.tipstrs.com/tip/1821/Fix--home-directory-after-installing-Leopard

You need to follow the steps in that tip... but this time there is more. When you upgrade to Snow Leopard, they move your existing /home directory to a new directory called /home-preserved. So once you follow the steps in that other tip, your /home directory will not be restored, it'll still be sitting in /home-preserved.

To put things back to how they were, you need to follow the instructions in the tip above, then change the permissions and owner of the /home directory and copy or move everything from /home-preserved to /home.

Here are the commands you need to enter in the Terminal when you are in the root directory.

1) sudo chmod 755 home

2) sudo chown XXX home

3) mv home-preserved/* home

In command 2) you need to replace the XXX with your own user name. If you don't know this, do an ls -l and see the user name for the home-preserved directory.

It's a pain to do this, but it does work. Apparently Apple doesn't learn from their mistakes, they just figure out ways to make them worse.