Google Webmaster Central is hosting a live chat session this Friday at 9pm (PST), noon (EST). Adam Lasnik of Google posted some details at the Google Webmaster Central Blog.
Date/Time: Friday, March 28 at 9am PDT / noon EDT / 16:00 GMT
The location of this live chat has not yet been announced, but they will update this Google Groups thread with the details, when available.
It appears the Googlers will be viewable via a video camera on a web page. It also appears that they will allow users to call in, free of charge, and ask questions (I assume in a moderation queue). So all you need to participate is a phone, web browser, and an internet connection.
Googler's JohnMu adds:
Thanks for posting this, JLH! We'll add more details to the groups in the next few days.
I hope as many of you as possible can join in, it should be an interesting session!
As more details come out, I will update you.
Forum discussion at Google Groups.
Update: Details on how to join this chat can be found over here.