Some time ago, Hal Fulton had some good things to say about Apollo:

    http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/4815

I'm not familiar with it, but for those of you who are interested, I am 
posting a note that I recently received from YOSHIDA Kazuhiro:

# Hi. My name is Kazuhiro Yoshida aka moriq in Japan.
# 
# In Apollo ML, one member said in this way.
#   http://www.freeml.com/ml_view.php?ml=ap-list&pg=1398
# 
# (translated)
#   http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/7366
# 
#   I think that an interesting answer comes if I introduced Apollo to
#   the person who wrote this thread.  Because if it was Apollo, I am
#   usable with Linux and Windows.
# 
# Therefore I write an answer.
# 
# Apollo is a Ruby extension library of Delphi VCL.  Kylix can use
# only beta yet in Japan, but was able to port Apollo in at hand.  I
# am glad that I have you test Apollo as one of alternative in GUI
# with Ruby.
#   http://www.users.yun.co.jp/~moriq/apollo/index-en.html
# 
# Thank you.

And thanks for telling us.

Some brief quotes from that last link might also be of interest:

# What is Apollo?
# 
# I call Apollo as a whole system which connect Ruby and Delphi.
# 
# Apollo is under experiment and not fixed. Design may be changed.
# 
# What is Phi?
# 
# Phi is Ruby extension library to use Delphi's Visual Component
# Library(VCL). Usage is as same as other Ruby extension library. 

Conrad Schneiker
(This note is unofficial and subject to improvement without notice.)