This article might word it more clearly, from TORN:
PJ confirmed that the scouring of the Shire is out of the film. He explained that it just didn't fit cinematically and that the scene of the Shire destroyed in the mirror in FotR was their way of paying homage to Tolkien's message about the destruction of the English countryside with industrialization.
These are two interesting paragraphs from the link above: Also see above where maq brought clipping from a casting sheet that is interesting!
* Shelob WILL NOT BE in The Two Towers. Apparently, they've expanded the Frodo-Sam-Gollum-Faramir stuff quite a bit, and as such Shelob has been kicked to the beginning of ROTK. No word on how they'll end TTT. PJ wanted us to know so that "we wouldn't be disappointed." More Arwen too, they said.
* Fran Walsh wrote AND directed Gollum's backstory. So flashbacks of Smeagol and his birthday present will be in TTT.