Michelle Williams has signed on for Sam Raimi's Oz, the Great and Powerful in the role of Glinda, the Good Witch, Variety reports. The Disney release, a prequel to the 1939 The Wizard of Oz , will star James Franco as a younger version of the Wizard from the original film, who winds up in Oz following a balloon accident. Mila Kunis is also attached in the role of Theodora, another good witch while Rachel Weisz is in negotiations for Ev...