First Read:
http://creativi.st/blog/articles/2005/06/25/rails-oracle-client-on-mac-os-x
Then Read:
http://lists.rubyonrails.org/pipermail/rails/2006-April/035368.html
Finally did following in order for oci client to install
After 2 hourse trying to figure out why it was failing on OCIInitialize ... no
I found this post and after reading it went to /usr/local/lib/ruby/1.8/i686-darwin8.8.1 and changed CONFIG["CFLAGS"] to look as following:
CONFIG["CFLAGS"] = "-arch ppc -g -O2 -pipe -fno-common"
And CONFIG["DLDFLAGS"] to look as following:
CONFIG["DLDFLAGS"] = "-arch ppc"
Make sure to change it back though :)