I have a "free-style software project" job, that checkouts project from CVS. If I add a description to cvs commit that contains national characters (Polish in my case, e.g. ą, ę, ł, ó), Jenkins doesn't show these changes in changelog (in fact Jenkins show no changes for entire build containing such a commit, even though there are other commits not containing national characters).
But changelog.xml files seems to be generated properly.

I think this behaviour started after upgrading cvs plugin from 1.6 to 2.4 (but i am not 100% sure).

I also noticed a problem with jabber notifications, that may by connected to this issue. If a build contains such an "invalid" commit, then cvs commiters are not notified on broken build. I'm not sure, if these two issues are realy connected, but thought it might be helpfull.