At the risk of seeming a little bit self-serving, you can also look for
other editions of the autobiography, one of which is the edition that I
edited for University of Wisconsin Press -- Mark Twain's Own
Autobiography:  The Chapters from the North American Review.  The
original edition came out in 1990.  Wisconsin is planning a second
edition -- with a revised introduction and additional materials -- for
later in 2009.  In the introduction, I comment on the earlier editions
of Paine, DeVoto, and Neider.

The MTP edition will be the whole of the manuscripts that Twain
compiled.  It will be a very different kind of read.

Michael J. Kiskis
Elmira College