It’s time to rethink TV apps. Many of the top entertainment apps on the iPad today are essentially digital TV channels—both new and old (Netflix, Hulu, ABC, NBC). But these are basically just ways to watch regular TV shows on your iPad, computer, or big-screen TV connected to an Apple set-top box. They don’t really go beyond that or take advantage of the fact that they are, well, apps.

All of that could start to change soon. Tomorrow, Apple is expected to announce a new iPad and a new Apple TV. It is very possible the Apple TV tomorrow will be just an update to Apple’s current set-top box device—AKA, the “hobby,” not the mythical TV the company is also supposedly working on that was Steve Jobs’ last project. When Apple moves the product beyond hobby status, it will be an actual TV with a screen and computer innards. If it is successful, it will not only change the way TV shows are distributed, but could also change how we experience TV.

In its attempt to turn TV into more than a hobby, Apple is reportedly trying to convince the TV industry to turn their channels into apps and stream their video programming over the Internet directly to Apple TVs (as well as iPads, iPhones, and Macs). Presumably, these channels apps could be free and advertising-supported or charge an ongoing subscription just like magazine or other apps can today.

The prospect of streaming subscription TV delivered over the Internet is a direct challenge to the cable and satellite TV industry because it bypasses their distribution and their bundled billing relationships with consumers. The ability to pick and choose your channels or shows and pay only for the ones you actually watch is certainly appealing. But disrupting TV distribution is only half the story, and Apple certainly isn’t alone in trying to do this (so is Netflix, Amazon, Google, and Hulu).

The other part of the story has yet to be written, and it will be written by developers. Apple wants to turn TV channels into apps. What does that mean? So far we’ve only seen plain vanilla versions of TV apps. They are typically collections of videos from one TV channel or site organized in an easy-to-consume fashion. Sit-back TV works, and they don’t want to mess with it. But TV apps could deliver so much more than just video. They could deliver data, social commentary, and even geo-local context when appropriate.

For most TV apps, there should always be a veg out mode. That should be the default mode because that is the way most people watch TV. But it also depends on the show and what else you are doing. We are already multitasking when we watch TV. The rise of second-screen companion apps that you play around with on your iPhone or iPad while you are watching TV is a testament to how easily our attention drifts. When the TV show or game your are watching gets boring, many of us are increasingly turning to Twitter and other companion apps for entertainment (often to commiserate about how awful the shows are that we are forcing ourselves to watch).

Most companion apps today pull in filtered social feeds about the shows you are watching. Social streams like chatter on Facebook and Twitter are just a layer of data. Those streams could just as easily be available in the primary TV apps themselves. There should be a way to push the video to your big living room screen via AirPlay, while continuing to use your iPad or iPhone for the other data features.

But let’s tale this a step further. What other layers of data could be added to TV to make it better, and more engaging? I think that depends on the kind of TV you are watching. If it’s just mindless TV, adding “interactivity” could be a mistake. But if I am watching a movie with a great soundtrack, when the credits roll, why not link to those songs on iTunes? Or if I am watching a cooking show, let me download the recipe. A newscast or documentary could benefit from all sorts of additional footage, links, and charts. A travel channel could geo-target its shows.

The traditional lean-back videos, you throw on the big screen. And when you want to dig in and lean forward, you do it on your iPad or iPhone. It’s the same app running, just on two different screens. And if what’s on your iPad is more interesting than the video on the big screen or you want to share it with everyone else in the room, pause the video and throw the Twitter stream or data visualizations up there. Or don’t pause the video, just overlay it on the screen. Take control of the experience.

Right now, the only control you have over TV is to change the channel. What if you could essentially control the graphics, or dive deeper into areas you want to learn more about? The only way this is ever going to happen is if TV apps are designed to make such exploration feel natural. And it’s not going to come from the TV industry. People in the TV industry generally don’t think this way. They package up video and present it all ready to consume. No, the best TV apps are going to come from app developers who ask themselves how they can use software to make TV better.

So you tell me, what is a TV app?