Today new in the arxiv: "Cohomologie syntomique: liens avec les cohomologies étale et rigide".
Edit: Jan Nekovar announces an appendix to this article on "foundational aspects of syntomic topology and cohomology" (perhaps obtainable on request?) and mentions descriptions here and here.
Edit: It shows to be usefull to look (for the keywords in various languages) for exposé's of talks in the late 1980's explaining themes around Fontaine-Messing's article.

