So there's been an interesting side effect of using Jabber (specifically, Google Talk) to act an interface to the home automation system- logging. Google Talk allow for messages to be sent to offline contacts; these messages are saved and stored in the normal "Chat" dialog in the GMail interface. Since the automation system sends state notification to Google Talk, all of the messages are automatically archived in my account.
This is a nice little side effect. It provides a timestamp based on the browser's time zone and nearly ubiquitous access to the information. I also imagine that it'd be rather difficult to tamper with the timestamps. I now have a record of my garage door activity for the last several weeks (and indirect proof of my lack of a social life- I don't go out much apparently). My 9:30 Taco Bell run also will live in infamy.