This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Pretty much, yes. There's wiggle room in the Spec (unless that's changed) for containers to create multiple instances as they see fit, but from the developer's point of view, your code needs to be written so that multiple threads can access a single servlet instance.