In a tweet the inquisitive developer says that the Apple TV is indeed set up for apps and that you can actually install them with the OS in its current state:
So, not only is the AppleTV set up for installing applications (of UIDeviceFamily 3), but the installation actually works
At the moment there’s no way to run these apps, but considering the new Apple TV is jailbreakable, in theory at least, it’s fairly safe to say it shouldn’t be too long before some hacker finds a way to make the magic happen.
This obviously opens up all kinds of opportunities, possibly more so for the jailbreak scene than an Apple TV app store. Imagine if you will, a game running on your iPad, streamed to your Apple TV over AirPlay, with your iPhone as the controller.
The future is looking bright indeed!