Ive read in two different articles (and we all know that magazines are totally reliable:-P) two completely different things. One said that Idina and Kristin developed a very nice friendship. I mean even in Idina's tony speech, she told Kristin she loved her, and in a press interview where they were talking about Taye joining the cast and Kristin getting to make out with Idina's husband, Idina made a joke, and Kristin said "You better be glad I love you..." or something of the like. So maybe that is true...
But in the other, it said they had a work relationship, but not a realy "friend" ship. Who knows? I mean it'd be nice if EVERYONE on Broadway got along. But they don't.
However, on the Broadway.com video Marissa said herself that she and Laura Bell Bundy hated eachother in Hairspray, but when they both moved to LA, they started hanging out and got to be REALLY good friends. So maybe because Idina and Kristin had so much friction between their characters on-stage, they kinda channeled that in their own relationship (however, it wouldn't be such an extreme case as Marissa and Laura, because they two were in fact friends on-stage...)
*not a Wicked fangirl*
that's a really big mic...