Fact #1: Facebook's iPhone app is one of that platform's all-time most popular applications. Fact #2: Apple's iPad has been on the market for well over year. Why, then, does Facebook still have no native app specifically built for the Apple tablet? Perhaps that's soon to change. Reports emerged Friday that Facebook is indeed working on an iPad app. That follows rumors Thursday that the company is working on an HTML 5-based platform code-named "Project Spartan" to distribute Web apps to iDevices.