I was looking into mobile (Android and Apple) world, but was not convinced. Main thing: there is really little chance that somebody would fill out sweepstakes using smartphone or even tablet. Just because they?re TOO small and missing real keyboards and mice. So, most possibly, SL would stay on Windows platform.
And my opinion concerning SMS sweeps. Long time I?ve tried to stay away from them. Just because mobile providers were charging ?per SMS? rates, defying an idea of ?free for entry?. However, recently some providers introduced plans with unlimited SMS included, so now those SMS sweeps become more appealing. However, I still don?t want to move into mobile world programming. I?m thinking about some kind of Android emulator that would send SMS messages from Windows environment. Not sure, if it could be accomplished, but it worth trying?
For now, I can recommend Schedule Sms Wishes utility for Android that I?ve found:
http://https://play.google.com/store/apps/details?id=com.diota.android.smswishesIt?s doing everything you need from SMS messaging, except handling of end dates.