After the security services identified Hamas efforts to transfer the infrastructure for Kassam rockets from Gaza to the West Bank, an official verification of this trend has arrived. An article on the Hamas website warns: "The Kassam in the West Bank will be the main deterrent weapon in the next phase....The entire distance from Netanya to Tulkarm is no more than 4 kilometers. Ramallah and Bethlehem are adjacent to Jerusalem; the entire distance between Kalkilya and occupied Tel Aviv is no more than 7 kilometers." The article explained that intense efforts have been underway for the last two years in Jenin and Nablus to develop this capability. (Maariv-Hebrew, 5Jul05)
Here's a map of which parts of Israel are vulnerable to Kassams and Katyushas from the Defensible Borders website, which looks like it may become a very nice resource.