The After Effects CS5 Classroom in a Book (CiaB) is available.
This book introduces After Effects through a lesson-based approach, using step-by-step instructions to guide a beginner through the common tasks and workflows in After Effects.
To give an idea of what the book offers, the folks at Peachpit Press have made a few samples available for free. I recommend checking them out.
Here are links to the free samples, as well as some links to places on the Adobe website where you can go for more information about the same subjects:
Note: Because these samples don’t include the source files that are included with the book for you to follow along, you’ll need to use practice files of your own.