Many Fedora projects and groups use three IRC channels on irc.freenode.net for their regular meetings: #fedora-meeting[?], #fedora-meeting-1[?] and #fedora-meeting-2[?]. That makes it easy for people that are not part of the groups that is meeting to get involved with them or at least keep track of what they are doing.
Please note that the meetings in above channels normally get logged and the log often uploaded to public places (like this wiki or a mailing list) afterwards.
There are no general formal meeting rules -- but some of the groups have rules or guidelines like the FESCo meetings guidelines. Normally you are free to speak in meetings of all groups, but please stick to the topic and help make sure that the meeting is productive.
There is the Meetbot IRC bot in every channel to assist you with meeting summary and logging. The summaries and logs of past meetings can be found at the Fedoraproject Meetbot page.
Time table
The time table for the different meeting channels can be found in the Fedora calendar application:
Other Meetings
Sometimes groups meet out side of these channels, for example the Board Meetings.