You are viewing the documentation for Play 1. The documentation for Play 2 is here.
Play 1.1.1 — Release notes
You can read about the bugs fixed in Play 1.1.1 on the road map page.
This version is a maintenance release of Play 1.1 and is totally compatible. It just fixes important bugs of the 1.1 release.
If you come from Play 1.0, you probably want to see Play 1.1 release notes.