I am a "Java guy": search for "Java consultant" on any major search engine, I am the first non-paid-for link. I think this is because of my writing, but I am not sure.
While I think that server side Java is the greatest thing going (for server side development), I also find many other programming languages to be very productive: Common Lisp (and Scheme) and Smalltalk for research on new algorithms, etc., Python for small tasks (I have never used Python for large system development, although using Zope/Plone as a proof of concept, Python obviously is good for large projects), Prolog for search and NLP, etc.
I tried the Mono 9.x beta framework on Mac OS X a few weeks ago, and thought it looked OK. As we "speak", I am downloading the 1.0 DMG for the Mac - maybe I will kick the tires tonight if I have some time.
I think that the "Microsoft patent issue" with Mono is worrisome, but technically I think that the Mono project is very worthwhile.