Hi,
Logs are now kept from our public channels so that you can refer back to previous converations and catch up on things that happened while you were away if needed. They can also come up in google searches which can be useful.
If you would like a channel added/removed from the logging then please file an RT ticket by emailing linaro@rt.canonical.com and explaining your request. Note that only public channels can currently be logged.
Thanks,
James