A brewing Facebook-Apple phone battle? Plus 4 other Apple stories to read today

With so many people writing about Apple(s AAPL), finding the best stories and reports isn’t easy.┬áHere’s our daily pick of stories about the company from around the Web that you shouldn’t miss:

  • Fortune reflects on what happened last time a company tried to build an iPhone competitor by stocking its roster with former iPhone engineers.
  • If the varied metrics that hardware companies use to illustrate their phones’ popularity is confusing, do not miss Asymco’s helpful explanation of the definition of when a product is “shipped” versus “sold.”
  • After appmakers were warned by Apple to cease attempts at gaming iOS App Store ratings, downloads dropped off a bit in the month of April, according to PCWorld.
  • Ars Technica delves into how tech is changing healthcare, and among other innovations, how doctors are using iPads to explain procedures and diagnoses to patients.
  • More hints that Apple is working on new mapping technology for iOS 6. BGR has images of what the supposed maps’ 3D rendering would look like.