I had been carrying this idea around for a while and finally implemented it. Apple has a REST API for searching iTunes. I made a bot for Telegram that lets you subscribe to app updates. When a new version comes out, it writes to you in Telegram, whether in a private chat or a group chat. Now at work we will all be able to find out quickly when new versions of our apps go live in the App Store.
I wrote it in Node.js as best I could. The main thing is that it works. I wanted to make something for Android folks too, but it turns out Google Play has no API. None at all O_O.
Try the bot: https://telegram.me/ReleaseInformerBot (just type /help when you start)
If anyone wants to add something, the source code is on Github: https://github.com/makoni/ReleaseInformerBot
True, besides Node.js it uses my favorite CouchDB as the database. But to run it on a Mac, you just download the binary and you are done (well, and create the DB + views).