1) JRuby - A Ruby interpreter in Java, now your ruby apps can run in JARs and WARs inside of Tomcat or other Java servers.
2) ActiveMessaging - Letting Ruby chatter with JMS and all of the other apps connected to it.
3) Oracle DB driver - It exists and it works. What else do you need?
4) Rapid development. My team has gone from NOTHING to this: http://tripractix.com/extension/demo in a little under a year and a half. We started using RoR for simple prototypes, demos, and proof of concepts and stuck with it. We had some .NET components that took 3 months to write and stalled, we were able to rewrite those in RoR in 3 *weeks*.
Ruby is not the silver bullet for 'corporate IT' but it is certainly a viable option that offers significant advantages over other web-centric languages and frameworks.