I spoke with someone from Anywise Enterprises at CES this past year, and they told me about The Matrix, an iPad app (that's now out on the App Store) that will network a bunch of iPads together to create a video wall of whatever size you want. We've seen this idea custom implemented in art installations and design ideas before, but this is a one-touch implementation for broadcasting a multimedia installation across a set of iPads.
When we talked about the app at CES, I asked the developer to make a video of it and send it out when it was done, and sure enough, you can see the app in action after the break. He's only got a set of three iPads running it (1x3), but I was told it can run on any "rectangular" group of iPads, so if you have a wall full of iPads, you can run the video across each one.
The app is US$4.99, and you'll have to install it on every iPad you want to use -- there's no free version if you just want to receive a broadcast from another controller iPad. Still, $15 is cheap for a 1x3 video wall of something you'd have to code and design yourself. And if you have enough iPads to make a bigger Matrix, you can probably afford the app a few more times as well. Then again, if you're doing this regularly (for a trade show or demo), you would probably just use the same iTunes account and install the app across all iPads for the one-time cost of $4.99.