One of the questions asked numerous times at Dragon*Con was whether Shelob would make it into the movies or go the way of Tom. While I did not have a definative answer at the convention, my gut feeling said yes. The E Online Insider backs me up on this in his most recent Ask the Insider.
Specifically the Insider says, “The Shelob scenes haven’t been filmed yet, but the last time I talked to Sean Astin (Sam), he said he was looking forward to those. Shelob will be computer-generated, probably with some miniatures edited in.“
Source: E Online