'Connectors' are libraries written in various languages that directly interface with OpenWFE.
You could for example link directly your Ruby-on-Rails application to OpenWFE and thus gain enhanced BPM capabilities.
This .NET connector is written in C#.
Ryan McCahan wrote this Perl connector library.
It includes a Perl APRE (Automatic Participant Runtime Environment) for running autonomous agents reacting to workflow events, in Perl.
This connector is still looking for a maintainer.
Masa Saka wrote that Pnuts connector.
This was the first connector developed.
Ruby is a great language.