rvm does not find Ruby installed with macports

[Ronald Fischer]

On my Snow Leopard, I have Ruby 1.8.6 (copied from an old Darwin
installation), Ruby 1.8.7 (which came with the Mac), Ruby 1.9.1 (which I
have installed with rvm), and Ruby 2.1.1, which I just have installed
using macports. The respective pathes are:

/usr/local/bin/ruby                        # 1.8.6
/usr/bin/ruby                              # 1.8.7
$HOME/.rvm/rubies/ruby-1.9.1-p431/bin/ruby # 1.9.1
/opt/local/bin/ruby2.1                     # 2.1.1

Now when I do a

        rvm list

I get the output:

        rvm rubies

   macruby-0.12 [ i686 ]
=* ruby-1.9.1-p431 [ i386 ]

According to my understanding of rvm, it should honour the macport
installation, but obviously it doesn't. Why is it?

While we are at it, two more questions just out of curiosity: 
- What is that strange entry saying "macruby-0.12"?
- Is there a way to teach rvm to also recognize the rubies in
/usr/local/bin and /usr/bin?

Ronald
-- 
Ronald Fischer <ronaldf at eml.cc>
+  If a packet hits a pocket on a socket on a port, 
+  and the bus is interrupted and the interrupt's not caught,
+  then the socket packet pocket has an error to report.
+		(cited after Peter van der Linden)