Apple isn't allowing time limited demos, probably because it will severely cut into impulse purchase revenues in the App store, as well as create a lot more app cracking/theft opportunities. But here's an idea that will allow users to test apps, but won't let any apps escape onto the user's devices without them paying. Allow demo's to be downloaded to the iPhone demo models which are locked-down to tethers in the Apple stores. Apple can run some special OS configuration/provisioning on these devices so that they can either download for free, or reverse the App store purchase charges auto-magically after some demo period. Add a checkbox on the developer submit/control page so that developers can opt-in or opt-out of this demo opportunity, on a per application basis. Then, just like you can try-before-buy some new iPod model in the store (but not at home), you can try before buying most apps in the store as well. so?