I MUST be overlooking it somehow.
I haven't run too many campaigns there but unless I was overlooking too, I never did notice any day parting features.
We tested PopCAsh recently and I was surprised that they have no some general targeting capabilities like Carrier targeting, Phones/tabs.
They have only Country, Category and OS tergeting for now. Also you can create a blacklist or whitelist.
Though some guys say it works well for them.