Get it from http://www.jboss.org/picketlink/downloads
Please refer to the Release Notes : https://docs.jboss.org/author/display/PLINK/v2.1.1.Final
Differences between PicketLink v2.0 and v2.1 are listed here: https://docs.jboss.org/author/display/PLINK/Differences+between+PicketLink+v2.1+and+v2.0
We are still testing and fixing bugs we find. PicketLink v2.1.2 should be released soon (few days).
Give it a spin.