Ban them. Immediately.
It's as simple as that.
Maybe allow a few days to pass for current maple bat users to get their affairs in order and get some new bats shipped out to wherever they're playing at the time. After that, these weapons of mass destruction should be banned from Major League Baseball altogether.
It's simply not safe for the hitters, catchers, players on third base (Brady Clark spearing Carlos Delgado at third base in spring training), and especially umpires.
Though Carlos Beltran probably wishes he was using a maple bat last night.
Get them out of the league before someone is seriously injured, because I guess bleeding from the head isn't serious enough.