Microsoft has published new Vista tool called Group Policy Log View. Its name tells everything about its purpose. Vista's GPO processing takes advantage of new event logging subsystem Crimson and stores a lot of data about GPO processing in event logs. This tool allows You to create TXT, XML or HTML report from these events.

Report can be generated from live logs or from off-line log file.

I think that one of useful troubleshooting option in this tool is -m switch, which turns on monitoring mode. This mode is showing GPO related events in real time. Another useful switch for troubleshooting is -p which dumps process ID correlated with event.

It looks like gpLogView is another must have tool for Active Directory administrators with Vista clients.