They've done it with the camera. They've done it with Touchless Control and Migrate. They've even done it with the FM Radio from the brand new Moto G. Now Motorola is moving even more of its proprietary phone apps into Google Play Land, presumably to allow for more frequent and reliable updates. Today Motorola Assist and Motorola Connect, both exclusive to the Moto X and Verizon's new Motorola DROID phones, are available on the Play Store.
Motorola Assist is a pretty basic automation app that will change a few settings based on time or location. In driving mode it can automatically start a music app and read out text messages or incoming callers. It's also got a sleep and "do not disturb" function, which will silence calls and texts during regular sleeping hours or for a pre-set amount of time for a meeting or movie. The app can also auto-reply with a canned response.
Motorola Connect is more interesting, at least if you've got a new Moto phone and you spend most of your day on a computer. The app connects with this Chrome extension to alert you to new calls or text messages on your PC (like Google Hangouts will do if you use a Google Voice number). You can even reply to text messages using your own number.
There don't appear to be any significant changes to the apps themselves, so Moto X and DROID owners are unlikely to see any new features for the time being. You don't need to re-download the apps; they should already appear on your My Apps list in the Google Play Store.