Twitter via the normal Service or Twittermail
You need an Email service on your Webspace. It won't work with Mailservices like Googlemail oder Gmx.
Thats a problem with your Webhoster. For example on byethost, it takes up to 30 minutes until your twitter status is updated.
I am still waiting for the plugins approval trough Ping.fm. If they approve it, you only need your
User Api Key. Until then, you must request a developer Key.
You can get your User Api key here: http://ping.fm/key/. The additional API Key is required to enable the communication between Schmie-twitter and Ping.fm. You can make the request here: http://ping.fm/developers/. I made some Screenshots of this procedure. Have a look at my page: http://schmiddi.co.cc/wordpress_plugins/.