Apparently Cisco has added a feature to log configuration changes
Configuration Change Notification and Logging
Releases of Cisco IOS software prior to 12.3(4)T/12.2(25)S lack the ability to track the origin of changes to the running configuration. The only way to determine if a Cisco IOS software configuration has been changed is to pull the running and startup configurations offline and do a line-by-line comparison. This comparison will identify all the changes that have occurred between the two configurations, but it will not specify the sequence in which the changes occurred or the person responsible for the changes.
The Configuration Change Notification and Logging (Configuration Logging) feature allows the tracking of configuration changes entered on a per-session and per-user basis by implementing a configuration log. The configuration log will track each configuration command that is applied, who applied the command, the parser return code for that command, and the time that the command was applied. This feature also adds a notification mechanism that sends asynchronous notifications to registered applications whenever the configuration log changes.
This is something people have wanted for years !!!