mongrel and rails3

Trying to use rails3 with mongrel. It got error out.
Find this post: http://jan.varwig.org/archive/rails-3-and-mongrel

Put those lines into Gemfile
gem “mongrel”, “1.2.0.pre2″
gem “cgi_multipart_eof_fix”
gem “fastthread”

But using "mongrel_rails start" still not working.

It's fine when using "rails server" to start the mongrel_rails.

gem install mysql2 fails.

It turn out need this package 'libmysqlclient-dev'.
Under Ubuntu 10.04 , 'sudo apt-get install libmysqlclient-dev'.