From the Instapaper weblog:

We’ve been working on Instapaper’s Apple Watch app intermittently since December and we’re really excited by the possibilities this new interface opens up. We’re sure you’ll enjoy using it as much as we enjoyed building it!

The Watch implementation of Instapaper looks really slick. You can navigate your saved articles and begin text-to-speech playback from your iPhone. If you’d like to read along, launching Instapaper on your iPhone brings you to the exact position of the article being played.