Yep, you can play any character up to level 13 for free Friday, Saturday, and Sunday. Just start downloading as soon as you can, it's been about a 3 hour wait for me.
http://us.battle.net/d3/en/blog/4963739/Diablo®_III_Open_Beta_Weekend-4_19_2012
http://us.battle.net/d3/en/blog/4963739/Diablo®_III_Open_Beta_Weekend-4_19_2012
