Who owns the Copyright on the Papers you publish?

When you publish a Scientific Paper who owns the copyright? I know most of us, naively, still consider our work to be our own. But according to New Scientist the American Physical Society will not publish two papers in Physical Review Letters because the authors had asked for a rights agreement compatible with Wikipedia. Normally you transfer the copyright to APS before publishing and hence your figures can't be used on Wikipedia and the like.

Change is happening in the scientific community. We are starting to really think about how we publish our science. But being scientists we put practical solutions (such as the brilliant ArXiv) above the true solutions. Science thrives on the free sharing of ideas and we should be at the forefront of movements like Creative Commons not playing catch up. Free sharing of ideas can't just be within an ivory tower of scientists, especially when creationists and their ilk are banging on the gate. We need our work to be in the public domain more than ever. With Wikipedia a bare minimum.

I often think we need a figure head to galvanise us on this. We need our own Larry Lessig.