An initial version of the X10 Programmer's Guide for the 2.1 version of X10 is available here. Most of the concepts are the same as in X10 2.2, but some aspects have changed. We are in the process of updating the guide to cover X10 2.2.
The source code for the example X10 programs discussed in the Programmer's Guide is available as a zip file and can also be browsed online. Note that these examples are written using the X10 2.1.0 compiler and standard library.