So it looks like Ruby 1.8.3 doesn't play well with Rails (trunk) giving the following error:
./script/../config/../vendor/rails/activesupport/lib/active_support/clean_logger.rb:13:in `remove_const': constant Logger::Format not defined (NameError)
from ./script/../config/../vendor/rails/activesupport/lib/active_support/clean_logger.rb:13
from ./script/../config/../vendor/rails/activesupport/lib/active_support.rb:31
from ./script/../config/environment.rb:56
from script/server:42
Looking at the code.. we're just trying to remove it anyways so we can redefine it.. so simply check to see if its defined before trying to remove the constant.