Fixing WP from google panalties

Google will penalize you in some way for duplicate content. For example:
domain.com/some-post-i-made/
domain.com/p=12

Both render the same content. For new content, this is a non issue, for old content where WP did not use the “pretty url” method, I now have google indexing both url’s.

Yes, I can 301 redirect them out, but there are a lot, and this also poses a threat in that others could potentially poison your google rank simply by linking to the ‘id’ of your posts.

What can I do about this, I want to auto 301 redirect all p=x urls to the “pretty url” version. I think with a small SQL query this could be done. Anyone else even thought about this, or found a simple solution?