I have installed Python 2.6.6 on CentOS 5.4,
[@SC-055 lxml-2.3beta1]$ python Python 2.6.6 (r266:84292, Jan 4 2011, 09:49:55) [GCC 4.1.2 20080704 (Red Hat 4
It solved my problem for nokogiri in Centos
sudo yum install -y gcc ruby-devel libxml2 libxml2-devel libxslt libxslt-devel