I appreciate your interest in creating a plugin just for that purpose, but sadly Twitter Tools doesn't seem to work properly on WP 2.3.2--at least it doesn't on my install of 2.3.2. Your plugin works *perfectly*.
Also, even before When I was on WP 2, Twitter Tools would post to Twitter even when I would edit a post, with no way to tell it not to (unlike your plugin). Now, under 2.3.2, not only does it Tweet with every post edit, it pulls from Twitter my latest Tweets and miscategorizes them and assigns them to the wrong author. I've tried posting about this to Alex King's website, but he hasn't replied.
Perhaps I'll try tweaking your plugin myself, and see how far I can get with making a new plugin that simply cross-posts the subject title and URL. I'll let you know if I get anywhere with it and then, if you don't mind, perhaps I can release it on my own with the proper credit to you, of course.