This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
A container might create more than one instance if the servlet implements the SingleThreadModel interface. But that interface is deprecated and shouldn't be used any more, so this is kind of an academic example.