Ruby on .Net and Java
"You get the productivity of a dynamic language and the extensibility of these ecosystems," he (an industry analyst) said. "Dynamic languages don't have a lot of libraries. They often have trouble taking off because they don't have the library support you see with Java and .NET."
A lot of managers in 'enterprise' development environments are looking at Ruby, but considering whether it can fit into their ecosystem. I'd argue that ecosystems need to adapt, but JRuby and IronRuby may offer a viable alternative in the future.