G'day folks. I'm trying to introduce Ruby at work, and a few people are interested. However, I've been asked to present the benefits of Ruby over Python and PHP.
I've broken this down into 2 parts:
1) show Python and Ruby's advantages over PHP;
2) show Ruby's advantages over Python.
The first is easy. I'll explain things like:

Everything's an object.
Python and Ruby are easier to read and write.

For the second, I'm thinking of:

Ruby has many conveniences, which makes it easier to read and write. Eg: Optional brackets, and being able to open built-ins, allows for things like 2.days.from_now
RSpec is miles ahead of Python's TDD and BDD frameworks.
GitHub and RubyForge are fantastic resources for finding, releasing, and collaborating on software.

Do you have any suggestions? I'm all ears!
All 3 languages have their place.  As with any programming task you must pick the language best suited for the task.  Python has list comprehensions, php is much better when embedding and generating html.  Ruby is a great language too.  One of the things I have found myself using in ruby a few times is the 'a'...'zzzzz' to generate all possible strings of size 1 - 5.  They all have their advantages and are all better than the others at particular tasks.
Convincing others of Ruby over Python and PHP