Fortunately the RSS feed standard came to the rescue. We could create a super-simple server that would poll the Kompiler.no rss feed, and when detecting new posts would post a message to a Slack webhook. A super simple solution that had the nice bi-effect of being generalisable. RSS feeds are in their very nature generic, so an RSS feed polling server that notifies Slack can be used on any RSS feed and Slack channel really. Great!
This being Kompiler we ofcourse opted to implement the thing in Node.js using CoffeeScript. Not because we could not do it in another language, but because Node is very lightweight and easy to do web stuff with. The Node eco system is pretty great in terms of packages as well, and a ready to go RSS feed watcher package was available through the npm package manager.
The end result was a super simple generic rss-slack-integration package and a wrapper Node project to use this package for the Kompiler Ghost blog and our Slack group. The npm package weighs in at about 20 code lines, but it is my hope that it might be useful for anyone looking to have an rss feed update in their Slack channel.
Feel free to submit pull requests or file issues at the rss-slack-integration Github repository.