I'm working on mine and will be releasing it soon, but need to tweak out a few issues. It's already used on a few blogs, for example
Beer Steak - let me know if you'd like to beta test before it's officially released.
The way it works right now is that it automatically recognizes whether there is a picture embedded in the post and if it is, it will generate both HTML and BBCode codes at the bottom of the post. Text to go with it is customizeable. It also automatically posts generated links on attachment pages (so each image in the gallery has its own code).
All codes are SEO friendly, which is the purpose (to help you build up links with relevant anchor keywords).