IFTTT.com lets you specify a trigger and an action to be taken when that trigger fires. A trigger can be many different types of checks or conditions, e.g. you received an email from a particular sender, and the action can be to send another email (or post to Slack etc. - there are many services integrated).
This is very similar to Plone content rules.
Off the top of my head, we could expand the scope of a content rule to include specifying an IFTTT.com “app” (I think that’s what they call them). It would require authenticating with IFTTT.com and giving the IFTTT app a local (to the Plone site) identifier.
Or someone could create a Plone integration for IFTTT so that an IFTTT trigger could be something happening on a Plone site, and an action could be something done on a (another?) Plone site. Would require authentication to the Plone site(s) involved. This way Plone sites could be part of the IFTTT ecosystem and could participate in orchestrated (I haven’t gotten tired of that word…yet) action taking place on the greater Internet.
This would have security implications too.
Here’s a possible example: someone publishes a piece of content on a Plone site, which results in it being tweeted automatically. I know this is doable with Plone scripts or in a Plone add-on, or by manually clicking on a social media sharing button/portal action, but the point of an IFTTT app and an integration between Plone and IFTTT is that a non-programmer could do it.