I've made a Dutch translation for your nice plugin. I've made it already available through my own website, but I hope you will add it to the plugin so no extra steps are needed any more to use your plugin in Dutch.
The translation zip file can be downloaded here: http://www.burobjorn.nl/blog/wp-content/uploads/2010/03/limit-login-attempts-dutch-translations.zip
Thanks for providing your plugin to the community!
All the best,