title: How should I approach building a Universal iOS app that will include iOS 4 features, even though the iPad doesn't yet run iOS 4?
body: <p>I'd like build a game for both the iPhone and iPad.  As such, it would make sense to start this project from scratch as a universal app.  However, iPhone and iPad currently run two different versions of the iOS since iOS 4 isn't available for the iPad yet.  There are two iOS 4 features (GameCenter and iAd) that I would like to support in my game.  </p>
  
  <ol>
  <li>In this case, is it a bad idea to create this project as a universal app?</li>
  <li>If not, what are some thoughts I should take into consideration as I'm building a universal app that supports two different versions of the iOS?</li>
  <li>Is it somewhat safe to bet on Apple releasing the iOS 4 for the iPad in the fall as speculated?  </li>
  <li>If so, is there anyway I can begin building these iOS 4 features (GameCenter and iAd) into my iPad version of my game?</li>
  </ol>
  
  <p>Thanks so much in advance for all your wisdom!  </p>
  
  <p><em>EDIT:</em> I understand this issue involves managing risks.  I'm aware of the risks, but I'm more interested in any tech design considerations related to building a universal app when the iOS is fragmented among the various iOS devices.</p>