I'm having trouble finding a solution to this problem. I'm getting the error

Please install the mysql adapter: 'gem install activerecord-mysql-adapter'

when I specify either ruby-mysql or mysql2 in my Gemfile. This has only happened since I've upgraded to Rails 3.1.0-rc1. I'm running OSX 10.6, Ruby 1.9.2.

cody$ rails c
/Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:71:in `rescue in establish_connection': Please install the mysql adapter: `gem install activerecord-mysql-adapter` (mysql is not part of the bundle. Add it to Gemfile.) (RuntimeError)
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:68:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:60:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:55:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/railtie.rb:69:in `block (2 levels) in <class:Railtie>'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:36:in `instance_eval'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:36:in `execute_hook'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:43:in `block in run_load_hooks'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:42:in `each'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/
mysql ruby-on-rails-3.1
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