Jessica Walter by Jeff Vespa/WireImage.com Jessica Walter by Jeff Vespa/WireImage.com

It isn't Kelly Bishop, but this will do rather nicely: Sources confirm to me exclusively that Arrested Development's grande dame, Jessica Walter, has been cast as hard-drinkin', faded, '70s-movie-star Tabitha Mills on the CW's fast-tracked-for-fall 90210 update.

To recap: Tabitha is the grandmother of the show's central teens, siblings Brenda Annie (Shenae Grimes) and Brandon Walsh Dixon Mills. As I reported yesterday, Lori Loughlin will play the pair's mother. The role of the dad (and Tabitha's son) has yet to be cast.

I don't know about you, by my excitement about this show just swelled tenfold.

This Just In: Dirt's Ryan Eggold has snagged the role of Ryan "the teacher."

Related:
" Hilary Duff Out, Degrassi Teen In at New 90210
" Exclusive: Lori Loughlin Is 90210's New Cindy Walsh