When updating to firmware 2.1 it was impossible to take pictures with the iPhone camera. All I could see were blank empty pictures.
I do not know what caused the problem, but i solved it with BossPrefs (v2.15b). An application which can be found with Cydia. When clicking on the more button you can choose ‘Fix User Dir Permissions’. Which sets the Library and Media dirs to user ‘mobile’ with all 775 permissions.
Now I can take pictures which are saved normally.