As we're evaluating whether we should build a Wordpress plugin and in that context I'm trying to figure out how Wordpress handles script tags in a post?
What's the default setting?
Scripts shouldn't go inside the body of a post, but it is possible for administrator level users.
If you need JS inside a post, chances are you're approaching it from the wrong angle, content should go in the content area, not code.
However if you're looking to run code when something specific appears in a post, a better approach(imho) is to use a shortcode(or several), you can read more about them here.