I recently blew away all my developer tools, /usr/local and /opt (mac ports), and wanted to start with a clean install of my development tools. The following is my configuration for Ruby, Rails, iPhone and C++ development:
Cleanup was done by removing the developer tools with the include perl script:
sudo /Developer/Library/uninstall-devtools --mode=all
Then I deleted /opt, which nuked all of the old macports I had installed.
Then I cleaned out everything I thought I could from /usr/local/. I was mostly interested in removing the include, share, and lib folders from there. Just to be safe I didn’t delete them outright, rather I moved them to a ‘deleteme’ directory while I made sure I could get everything working again.
Once cleanup was done, it was onto the reinstall.
Install the developer tools, I grabbed the latest by downloading the iPhone SDK from the ADC
sudo port -v selfupdate
sudo port install subversion +bash_completion git-core +bash_completion+doc+gitweb+svn ruby rb-rubygems rb-rake curl xercesc boost log4cpp cppunit mysql +server
sudo gem install rails