Don't experiment on the App Store
The bottom line is that if I were an iOS developer, I would be leery of investing significant resources into a Today View widget.@TidBITS source
Unless you have time to explore (and see how it goes) DO NOT EXPERIMENT on the App Store. Do you have in mind a new feature? Toss it out as quickly as you can, submit it and see how it goes. DO NOT PUT SWEAT AND BLOOD IS SOMETHING THAT YOU ARE NOT SURE IT WILL BE APPROVED.
Widgets are a new feature in iOS8 and Apple is still trying to figure out the rules. If you want to experiment, just do it, and share the results with the community!
If each one of us runs a little experiment like James Thomson did, I am pretty sure we can figure out the rules.
UPDATE: Looks like Apple changed its mind. My point still stands though.