None of us can stop talking about the possibility of Idina Menzel playing Rachel's mom. Even if it turns out not to be the case, I think we're still going to be throwing that idea around. But, since the Glee creator/writer team and the cast won't reveal anything (they're just so good at keeping secrets, all of 'em), E! Online decided to go straight to Idina Menzel herself:
"There is much more to [Shelby] than has been revealed in the first episode that I was in.... I will say that her intentions are not quite evil. She's going to unravel more and show a different side to her personality."
Catch more spoiler tidbits in the entire article interview here.