I work under the assumption that I am the producer and keep all the required 2257 crap accordingly. The images appear on my site, and I therefore feel I am responsible for maintaining all the necessary records.

The PerMinute sites consider themselves secondary producers, which I don't get, but maybe they tell their attorney how to think. Most contract with "studios" in eastern europe, and they are usually listed on their 2257 pages as the primary producers.