That's what Fred thinks at About GPS:
So, is it even still possible to use a smartphone golf GPS app under local rule? Most smartphones, such as the iPhone, have default weather apps installed, for example. The iPhone's weather app is part of its operating system, and cannot be deleted, so the iPhone is not legal under this ruling. Less obviously, apps such as the default web browsers installed on all smartphones are probably not compliant, since you could look up all types of information on a browser.
Further probing of this ruling has revealed that the USGA considers it okay to carry a smartphone on the course with prohibited features, as long as the phone isn't being used. It's okay if it's in your bag or pocket, but not if you're using the smartphone on the course. I have contacted the USGA for its response to the effective smartphone ban caused by this rule, and will update here if additional clarification is provided.
What do you think? Did the rules change in 2012? Can smart phone GPS apps be used legally (when sanctioned) or are they now non-conforming?