Here is a solution to make all of your apps visible again if you had them in Categories folders and they've gone missing after the 2.2 update:
1. Go to your Settings
2. Go to "General"
3. Go to "Restrictions"
4. Enable Restrictions
5. Enter in a passcode and confirm
6. Disable Restrictions
All of your apps should be visible again.
1. Go to your Settings
2. Go to "General"
3. Go to "Restrictions"
4. Enable Restrictions
5. Enter in a passcode and confirm
6. Disable Restrictions
All of your apps should be visible again.