This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
As a tiles user, I would describe it as a templating framework which tries to achieve centralization of layout-code and layout-logic. That is, Tiles provides a mechanism whereby all of the web application's layout-code and layout-logic can be in one spot, and not strewn amongst all the various JSPs. See the Tiles features blurb for details. -Jim