Ruby programming language now can be called as mainstream programming language. If you are still not sure, checkout the site http://www.tiobe.com/tpci.htm according to which Ruby now got the 13th position from top. I liked Ruby always and still prefer Java for enterprise level. Java has continued to maintain the top position and will remain there for years to come. I am sure that Ruby will gain the position in coming months and prove its strength as a mainstream language. I am fan of both these languages. Oreilly Ruby blog has also post written by Curt Hibbs a post titled Ruby declared "mainstream", check that out.