The Chronicle of Higher Education, linked above, has several excellent pieces about Presidential libraries, including a discussion of the current controversy over the George W. Bush library at SMU. (you can visit a blog maintained by Benjamin H. Johnson, an assistant professor of history who is one of the leading critics of the proposal here)
But this article goes way beyond, with bunches of history on the development of presidential libraries, beginning with FDR. The Chronicle includes a wonderful table with links to all the presidential libraries, and notes on what federal law governs each one. It changes over time, from the Presidential Libraries Act of 1955 , which considers the papers the personal property of the former President. That means, for instance, that the President may pick and choose what is given, and that the Freedom of Information Act does not apply to the collection.
More recent libraries, have different laws that apply. This began with Richard Nixon's library (formerly private and now moving to become public), when he ordered the National Archives to destroy many of his materials, and Congress moved to pass the Presidential Recordings and Materials Preservation Act, to prevent this destruction.
And the most recent presidential libraries, from Reagan forward, are governed under the Presidential Records Act of 1978, and now the Presidential Libraries Act of 1986 modifies treatment. You can see full text of all the other acts, regulations and executive orders governing presidential libraries here. This excellent material is all fromthe National Archives, Presidential Libraries site.