Installing mysql2 gem for Ruby on Rails with Mac OSX 10.6

I am having a problem installing the mysql2 gem.

This comes up when I do gem install mysql2:

Marks-MacBook-Pro:~ Mark$ gem install mysql2
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
ERROR: Failed to build gem native extension.

/Users/useruser/.rvm/rubies/ruby-1.9.2-p136/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
checking for mysql_query() in -lmysqlclient... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/Users/useruser/.rvm/rubies/ruby-1.9.2-p136/bin/ruby
    --with-mysql-config
    --without-mysql-config
    --with-mysql-dir
    --without-mysql-dir
    --with-mysql-include
    --without-mysql-include=${mysql-dir}/include
    --with-mysql-lib
    --without-mysql-lib=${mysql-dir}/lib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-mlib
    --without-mlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-zlib
    --without-zlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-socketlib
    --without-socketlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-nsllib
    --without-nsllib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-mygcclib
    --without-mygcclib
    --with-mysqlclientlib
    --without-mysqlclientlib


Gem files will remain installed in /Users/useruser/.rvm/gems/ruby-1.9.2-p136/gems/mysql2-0.2.6 for inspection.
Results logged to /Users/useruser/.rvm/gems/ruby-1.9.2-p136/gems/mysql2-0.2.6/ext/mysql2/gem_make.out

Also when I use rails server this comes up:

Could not find gem 'mysql2 (>= 0, runtime)' in any of the gem sources listed in your Gemfile.

It seems that it cannot find the MySQL library. Have you installed MySQL?
Try installing it via homebrew:

brew install mysql

or install it via macports or fink or whatever you prefer.

Then try again with:

gem install mysql2