Warning: some libraries could not be installed
The following gems could not be installed, probably because of an
Internet
connection error:

 * mysql -- --with-mysql-config='/usr/bin/mysql_config'

These gems are not required, i.e. Ruby Enterprise Edition will work
fine without them. But most people use Ruby Enterprise Edition in
combination with Phusion Passenger and Ruby on Rails, which do require
one or more of the aforementioned gems, so you may want to install
them later.

To install the aforementioned gems, please use the following commands:
  * /opt/ruby-enterprise-1.8.7-2011.03/bin/ruby /opt/ruby-
enterprise-1.8.7-2011.03/bin/gem install mysql -- --with-mysql-
config='/usr/bin/mysql_config'

 * mysql -- --with-mysql-config='/usr/bin/mysql_config'

Make sure the path to the mysql_config is fine. It usually resides in
/usr/local/mysql/bin/mysql_config (if installed through the .dmg files) else
if it is installed through the ports then it will reside in
/opt/local/mysql/bin/mysql_config

--
Thanks,
Santhosh