Tennis icon Billie Jean King still has a formidable forehand. We know because after her talk at the Simmons Leadership Conference this week, King, winner of 12 Grand Slam singles titles, picked up a racquet and hammered a few balls around the auditorium. Other speakers at the annual conference included Hewlett-Packard president and chief executive Meg Whitman, Zipcar cofounder Robin Chase, and NPR’s Michele Norris. The Simmons conference is the longest-running women’s leadership forum in the country, and annually attracts a global audience of 2,500 business and professional women. The event was held at the Seaport World Trade Center Boston. . . . Word is actors Tom Sizemore, Robert Carradine (“Revenge of the Nerds’’), Michael Bowen (“Cabin Fever 2’’), and Jarrod Bunch (“Don King: Only in America’’) will join director Rebekah Chaney at the April 14 screening of “Slumber Party Slaughter’’ at the Boston International Film Festival.