There is a vast majority of players overlooking the forums which contain a lot of information including, tips, rules, and regulations in-game for a healthy PG community.
Seeing that the system can periodically send announcements, why not allow for it to send FAQs? It also reinforces what is being told in chat, and perhaps these FAQs can also be turned on and off.
e.g. "Please speak only English in the all channel; use the command /cgjoin x to enter x language channel."
"To add players, use the command, /friend username"
"Foul or inappropriate language is not tolerated on any premise of the game."
"You have been logged in for x hours."
I think it could also make use of the dark loading map screen, too.