on a new OS X Lion, I tried to install bpm, I expected that it actually works out of the box now (the gem installation required ruby and gem versions which my fresh Lion setup di not fulfill), but what I got what this:
bpm --version
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:30: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:36: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:40: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:30: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:36: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:40: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:30: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:36: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/yaml.rb:40: warning: already initialized constant ENGINE
/usr/local/ruby1.9/lib/ruby/1.9.1/date/format.rb:8: warning: already initialized constant MONTHS
/usr/local/ruby1.9/lib/ruby/1.9.1/date/format.rb:14: warning: already initialized constant DAYS
/usr/local/ruby1.9/lib/ruby/1.9.1/date/format.rb:19: warning: already initialized constant ABBR_MONTHS
/usr/local/ruby1.9/lib/ruby/1.9.1/date/format.rb:25: warning: already initialized constant ABBR_DAYS
<internal:lib/rubygems/custom_require>:29: stack level too deep (SystemStackError)