Ultimate Productivity Bundle by Readdle
First off, a developer is more than welcome to assemble a bundle, but it can only contain the apps made by a single developer. As of now there is no way to create a bundle with apps from more than one developer, but hopefully that's something that will change in the future.
Something interesting from Denys is that each bundle contains a “main” app, and that main app is used to determine where the bundle gets listed. So to use Readdle's Ultimate Productivity Bundle as an example, if PDF Expert 5 is set as the main app, that entire bundle is listed under Productivity. If Scanner Pro is chosen instead, it will show up under Business.
Luckily, bundles don't hamper cross-communication between apps, so just because you don't buy a bundle doesn't mean the interoperability is limited. This is great news, since it won't matter whether or how you got the apps, you can still take advantage of the new functionality (if developers have added it).
This is just one of the new features of the App Store, and earlier this year at the WWDC keynote we were shown several more, which we will soon cover here at TMO!