The event is scheduled for March 7th (Wed) in San Fransisco 10am PST or 1pm EST. Here are several places to watch the event live:
http://techiezlounge.com/watch-live-streaming-of-ipad-3-event-ipad-3-event-timings.html
http://www.droolable.com/apple-ipad-3-event-live-streaming-online
Read about it from the following blogs who will be posting live: