I played with some parsing of the toolbox log files, in %appdata%\esri\desktop10.0\arctoolbox\history, and I have found cases where the history xml-files contain bugs:
If there is a failure, there are occasions when a <type> tag gets inserted, which never gets closed
I have also found history xml-files which are not closed by an ending </ResultViews> tag
Just a word of caution, if anyone else is parsing these files!