On OSX, the OpenSSL version shipped with MacPorts is 1.x.x, but Ruby 1.8.6 requires an older version.

Therefore RVM comes with 0.9.8n that can be installed with

[bash]rvm package install openssl[/bash]

Alas, it was not working for me, so I ended up manually downloading that version, running

[bash]
./configure darwin-i386-cc
make
make install
[/bash]

Then install ruby 1.8.6 using RVM

[bash]rvm install 1.8.6 –with-openssl-dir=/usr/local/ssl[/bash]

Now I can hopefully do some damage in the Facebook Hacker Cup.