AFAIK you can't find out when you last did a cvs update, but
you can get something that works just as well: You have a bunch of
files checked out on particular revisions, and those revisions each
have a date in CVS. The date you need is simply the most recent such
date. You could write a little script to do "cvs stat" on all the
files and extract such a date. (I don't see any better way to do it.)
