JS_Harris - 9:54 am on Mar 20, 2010 (gmt 0)
The dot com boom of the late 90's saw me start training several dozen new employees weekly. I wasn't a pro at public speaking or holding 3 hour meetings several times a week before then but I knew my area of expertise well and I cared enough to make sure everyone got the most from those long sessions.
My tip - speak about something you are passionate about and let the audience set the pace of how much or how little gets covered. Include them as much as possible in the process without losing momentum or letting them derail the session into other subjects and you'll do just fine.