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.
You can think of portlets as mini application windows existing cohesively on a page.
One real life example of a portlet is iGoogle which allows you to customize your page with "widgets" These widgets are the portlets