They do. The IDEA language plugins provided by JetBrains and the respective standalone IDEs are kept in more or less in sync in terms of features. So The IDEA Ruby plugin has the features of RubyMine, the Python plugin has the features PyCharm.

http://www.jetbrains.net/devnet/docs/DOC-1146 http://www.jetbrains.net/devnet/message/5255649

Having Ultimate Edition you get Ruby, Python, PHP along with Java technologies and languages.

Web IDE, RubyMine & PyCharm are just 1 plugin editions for less price.

You sort of have this with IntelliJ, which I use for Java, Scala, and Clojure. (Also supports Ruby, but I prefer RedMine, or a non-IDE like GEdit or TextMate)