1.11.1 is a port of release 1.11.0. It will run on the newest Rubies (Ruby 2.0 - 2.4 and beyond). 1.11.0 will only run on Rubies up to 2.2.
If you have a 2.x Ruby, you should run this release. If you have a 1.x Ruby, you should run the 1.11.0 release.
All future Virtual Wiring releases will run on only 2.x Rubies.
To learn the version of Ruby you are running, type "ruby -v" at your command prompt.