Thanks to Tony Ruscoe who did some digging around Google Calendar, we have a "changes" file meant for internal eyes only. The file he posts is mirrored since Google removed the changes file soon after it was discovered.
"Logs estimate: I count about 317 records/day/server. I see on average about 1.4 clienterror-count entries/record so therefore 20 + 8 + 2 * 8 (1.4) ~ 50.4 bytes/record. Hence 15.9k bytes/day/server * 113 servers ~ 1.8Mb/day extra to temp logs. This is uncompressed."
In addition to the changes file, he also found a button that will let you search "public events" and some strange links at the top labelled "Google Internal IP Visible Info:".