Google isn't the only one with a sweet tooth for cross-platform apps. Apple's own gestating app merger -- code-named "Marzipan" -- is set to launch at WWDC in June, according to Bloomberg's Mark Gurman. Apple will reportedly start by giving devs the ability to port iPad apps to Mac. It will apparently expand the software to include iPhone apps next year. And by 2021, Apple's grand plan to let developers merge Phone, iPad, and Mac applications into one app will be complete -- meaning they'll no longer have to re-write the underlying code for their software, nor will they have to submit their work to different Apple App Stores.