FileUtil.remove_entry_secure seems to be broken in my version (1.8.4).  I get:

undefined method `fu_world_writable?' for FileUtils:Module
/usr/lib/ruby/1.8/fileutils.rb:680:in `remove_entry_secure'
#{RAILS_ROOT}/app/models/entry.rb:26:in `process'
./script/../config/../app/controllers/image_manager_controller.rb:23:in 
`process_upload'

Any ideas?