The most up to date documentation for openbabel seems to be here:
http://open-babel.readthedocs.org/en/latest/
Why this is not linked anywhere in the http://openbabel.org website ???
The website seems outdated anyway as the News page says nothing about 2.3.2 release.
Also the wiki says nothing about Rubabel http://rubygems.org/gems/rubabel which seems the most recent bindings for Ruby