Still haven't found the whole text online anywhere, but there are a few great write-up's of the First Lady's speech to Corporate Voices for Working Families here, here, and here.
Among the quotes:
"Twenty-two million working women don't have a single paid sick day. That means they lose money any time they have to stay home to take care of their kids. You know, imagine making that choice. And we do it all the time. And even when I had sick leave, I found myself, you know, hoping that the kids would stay well, just I couldn't afford to take the day off because there was a meeting, or something was going on."
Now is definitely the time to ask your legislators to co-sponsor and vote for the Healthy Families Act. Think of it as the Mother's Day present (and Father's Day, and Grandparents Day...) that keeps on giving.