Here's the long story:
At one time we built the jars from an ant task - 'jar-all'. All of the jars that are in the lib/main directory were packaged into the jar, with some exclusions. From reading the task now it appears the json-xxx.jar would have been included. At the end of 2010 we switched over to building the jars with maven. I'm looking at the pom file and there is no dependecy on the org.json library. There is nothing in robolectric that requires the json jar, so there's no dependency, and therefore the 'with dependencies' jar does not include it.
The short story:
Robolectric used to include it, but now it doesn't.
While it seems the with dependencies jar should include org.json, it does seem wrong to depend on the jar if its not required. I could be convinced either way.
I'm sorry you've had to waste time wondering about it. If you're having this issue, then others are probably too. I guess that means we should add it to the pom. What do you think?
--Tyler