Manning has published two sample chapters for Tapestry in Action.
Chapter 02 introduces the basics of Tapestry, and shows how to use DirectLink, Conditional, Foreach and Image components.
Chapter 05 skips ahead a bit and discusses Tapestry input validation subsystem, which is very powerful. Alas, the screenshots were done a couple of months ago, and show the older, uglier version of the DatePicker component.
I think it was Geoff who suggested chapter 05, something along the lines of "let's blow the tops of their heads off!"