Discussion on:

Researchers find iOS is rich target for spying software

calls for the use of a portable devices accelerometer, in cooperation with a specialized controller, to detect whether a theft condition is present and sound an alarm.

How do they plan to tell "theft" from running to catch a cab?

...How the right parameters would be set and configured for "theft movements" is a little vague. In your scenario, I think it would sound an alarm that could be disarmed by the authorized user (say entering a key sequence or password) that would tell it, hey no, it's just me! Here is the link to the patent explanation with some rough graphics: http://appleinsider.com/articles/12/11/01/apple-continues-work-on-anti-theft-systems-for-idevices

If I run really fast on my morning jog, would they think my phone is stolen?

What, are they looking for parcour moves or something?

Maybe you have to program in your height/weight and general fitness level, and the program determines there's no way you can move that fast?

And what will sounding an alarm do?

When was the last time anybody went running to the rescue because they heard a car alarm going off?

So if your device has never been jailbroken you're safe from spyware. Right??

While at some point there may be some clever browser exploit, if the Apple app store controls/sanitizes every app, then realistically there is no malware point of ingress for a locked phone.

I think it's a bit paranoid to assume that someone would physically obtain, jailbreak, and install apps on your phone. If somebody is that close to you, then why would they need to perform surveillance on your phone?