Joe,

 > 1)  Why one additional language isn't a bad thing

Because if we never had one additional language we would still be using 
Cobol. Ruby is just the next step you take after Perl and Python.

 > 2)  Examples of existing Ruby usages in large scale applications

We build large applications for "huge companies that [fly] really big 
expensive things". We switched to Ruby in January of this year and have 
not looked back since. Ruby is an excellent platform for large-scale 
application development in my opinion because of the excellent namespace 
system, speed of development, code maintainability, and speed of 
execution. Our Ruby system currently services over 200 airlines (all 10 
of the top 10), 800 aircraft part manufacturers and repair facilities, 
and more than a thousand part suppliers. We deliver data on 350,000,000 
inventory items and 2 million repair capabilities to 8,000 users.

 > 3)  How Ruby can benefit this place

Ruby will save money because development and maintenance are faster and 
easier. You need less experience to use Ruby than Perl or Python. People 
can become productive more quickly.

My 3 cents

Dan