Apple:
Apple CEO Tim Cook will speak on February 14, 2012 at approximately 12:30 p.m. PT. Listen to the Audio Webcast here.
As far as I know, Apple has never webcast these kinds of speeches in the past.
Tim Cook speaks at the Goldman Sachs Technology and Internet Conference
As pointed out to me by
Eric Slivka, Cook has done this kind of live webcast in the past.