As recently as SC2002, one of the authors of the PVM book... http://www.netlib.org/pvm3/book/pvm-book.htmlsaid they were coming out with an update. Certainly it looks like they have been busy on http://www.epm.ornl.gov/pvm/pvm_home.html. To assist in your selection process, you may want to visit this link...
PVM and MPI: A Comparison of Featureson the ORNL page. Also, I believe there is a similar description in the MPI book.