I was able to find some verbage in the hub.log when a new robot is installed. I have my log level set to 3. Also thought about bumping this down even further (to 2 or 1) and see if I still get info in the log when a new robot comes online. Example from the log below: (obviously insert has been edited to remove IPs/servernames/etc.)
Oct 3 16:27:45:528 [1852] hub: robotup - {servername} {IP} 48000 [5.12 Aug 12 2010]
Oct 3 16:27:45:528 [1852] hub: ch_robotlist /{Domain name}/{Hub name}/{servername} 1
Oct 3 16:27:45:528 [1852] hub: robot added: {servername} {IP} 48000
Oct 3 16:27:45:528 [1852] hub: nns(+):/{Domain name}/{Hub name}/{servername} {IP}/48000
Oct 3 16:27:45:575 [1852] hub: nns(+):/{Domain name}/{Hub name}/{servername} {IP}/48000
Oct 3 16:27:45:575 [1852] hub: internal alarm - Robot {servername} is running, 0, {servername}
Oct 3 16:27:45:575 [1852] hub: ch_probe /{Domain name}/{Hub name}/{servername}
Oct 3 16:27:45:575 [1852] hub: probelist - {servername} {IP} (s:1650)
Oct 3 16:27:45:575 [1852] hub: nns(+):/{Domain name}/{Hub name}/{servername}/controller {IP}/48000
Oct 3 16:27:45:575 [1852] hub: probe port added: {servername} controller {IP} 48000
Not sure how much of these lines could be used in other contexts in the file. I would assume that the "robot added" and "probe port added" would at LEAST be unique for new robot installs. Working on a logmon profile that can check the hub.log to new installs and then send us an email letting us know the server name, IP, hub, and domain that the new server was added to.