Microsoft streamed a live webcast for the Office 15 event. The San Francisco conference is reported to be the announcement of the Office 2013 Beta.
When: The event starts at 3:00PM (eastern)
Who: Steve Ballmer will be speaking
What: News about the Office 2013 ( codenamed Office 15)
Where: Watch it via telecast at http://www.microsoft.com/en-us/news/presskits/office/liveevent.aspx ( this link is live and currently working)