Adam Lasnik of Google announced in a Google Groups thread that they are going to be hosting the third webmaster live chat event this Wednesday, October 22nd and noon (EST) or 9am (PST).
I am personally upset at the time. It is a Jewish holiday and I can not be online to participate, which means I cannot provide a recording and commentary after the session is done. I am sorry about that, but there is no way I can be online at this time.
They are planning on using the Google Moderator tool to facilitate the live chat, plus the audio won't require phone - as they are broadcasting the audio online. JohnMu will be covering a topic named "Scary Webmastering Myths" and there will be tons of Q&A time.
You do not want to miss these events, so make sure to stay tuned to the Google Webmaster Central blog for the official announcement. Personally, I hope they change the time before posting the official announcement (note, Thursday is fine, Friday is fine up until Sundown in EST).
Google's first webmaster chat event was back in March 2008 and the second event was in June. We have a full recording and transcript from the second event.
Forum discussion at Google Groups.
Update: It is now official, more details on how to join over here. The date and time are final.