As many of you working in the US may already know, the NIH has mandated that all federally funded research must be made publicly available. This is a laudatory (and long overdue) move that will benefit researchers everywhere  - I guess the only people unhappy with this will be some publishers!
Anyways, as of July 18, 2008, PubMed has published the list of journals that AUTOMATICALLY comply with NIH policies without any author involvement. If you do not publish in these journals, you may need to contact the journal directly, and/or manually upload papers to Pubmed Central in order to comply with NIH funding guidelines.

Check out my forum post in the General/Miscellaneous category for the full list.