Nesting app folders is presently available though this may be considered a bug that Apple will fix in a future iOS7.x.x update
First, combine two apps to create a folder, and then combine the remaining two apps to create a second folder.
Now, hold a finger on one of the folders so that it becomes grayed out.
As soon as it does this, press the Home button twice to bring up the multitasking menu. This trick will not work if the apps begin to wiggle (when they enter the organization mode) before you hit the home button. You have about a half a second to get this right.
From the multitasking menu, click on the home screen. You should see the folder icon remains enlarged and grayed out, and also that the folders are now wiggling.
Now, click the destination folder (the one you want to add the first folder to). You should see the icon of the first folder hovering above.
Now, click the Home button once. Ta-da! You now have a folder within a folder. The best part is that these folders work flawlessly, and you can navigate through them, launch apps from within them, and move apps just as you would otherwise.
You can use this trick to further nest additional folders, and I've been able to create five folder levels before eventually stopping, though I'm pretty sure you can just keep going until you get bored.
Here's a guide on how to create folders of apps within a folder of appssource: http://www.tuaw.com/2013/09/23/how-to-create-nested-folders-on-ios-7/http://www.tuaw.com/2013/09/24/how-to-create-nested-folders-on-ios-7/