I had first started to write a plugin to crosspost my entries because I wanted to unearth my personal blog on Movable Type whilst maintain my blog on Vox. Then, as things go, I started to work on other projects and the need for the ability to crosspost entries between Movable Type installations arose too so rather than create separate plugins, I decided to toy around with the idea of creating pluggable plugin!
In fact, I even got close to releasing the plugin a few months ago (a private alpha/beta was released to ProNet) but then real life took over and I was head down for a while. When Movable Type 4.0 was released, I was secretly glad I had never released this plugin because I was able to start again from scratch and create a much cleaner, easier to use and more extensible plugin than before!
But enough of my reminiscing, CrossPoster is a brand new plugin (built for Movable Type 4.0!) that, as it's name suggests, allows you to compose an entry on your Movable Type blog and then publish it to a number of other blogs. The beauty of the plugin lies in its completely extensible nature. CrossPoster makes use of a variety of connectors that connect your Movable Type installation to your crossposting accounts. These connectors make use of the Atom API (a standard that almost all popular platforms are compatible with) and are extremely easy to create (developer documentation will be available post-beta). By default, CrossPoster can publish to LiveJournal, Vox and Movable Type accounts (I was trying to find some information about WordPress and although the Atom API was implemented in v2.2, I could find no documentation or information on the endpoints, if anyone knows of these, do leave a comment!)
As the title suggests, CrossPoster is in a beta state so there is a good chance of bugs so you are advised to take a full back up of your database before installing or using this plugin. Please post any bug reports of support threads onto the CrossPoster beta testing forums