Yes, this is <A target="_blank" href="http://lekkimworld.com/2008/12/12/twitnotes_1_0_6_released_to_the_update_site.html">Notes on Twitter</A>. Twitter changed their API for verifying credentials last week and TwitNotes stopped working, so if you like the service, Mikkel Heisterberg has posted an updated version of TwitNotes that works with the new API.