Sony have said that they have two possible solutions to LBP players who create mature content (someone drawing a penis): self & community policing and the correcting power of legal action.
The first will be something similar to a user rating their own content, and then the community members who play it rating it too. If there is too much of a difference it is sent back to the author to re-rate it. The second is, like you’d expect, legal action.
However, it is fine if you create something obscene as long as you do not upload the level to the community, so you can still share it in your own circle of friends, regardless of how perverted it would be to see a cute little sackboy stood next to a penis that’s 5 times his size.
We can only assume that the mature content moderators will be called the Penispolice. That would be both cool and hilarious.