Facebook is introducing a text-based version accessible by those who don’t own smart phones or subscribe to mobile data plans.  TechCrunch reports that the company slipped the announcement for the service, called Facebook Zero, into a presentation at the Mobile World Congress.  Facebook described the service is a lightweight version of m.facebook.com that omits data intensive applications, and said the service will launch within weeks.  TechCrunch says the name comes from Facebook s description of the system as having zero-rated pages, a likely reference to its not-so-taxing data rate.   Read more at TechCrunch.