I first heard this phrase "on the ground" in relation to the Iraq war. President George W. Bush would often encourage waiting on any decisions regarding the war until we had heard from our military leaders "on the ground." The phrase seemed to mean a view from the trenches, a report from those directly involved. It was a way of parrying those who wanted to decide for themselves, from their safe seats in Congress, or those who were critical of the war.
The phrase has always irked me, for whatever reason. It strikes me as sort of anti-intellectual, that the real story can only be received from someone who is seeing the events in realtime. Perhaps this is true in some ways, but just because someone is an eyewitness doesn't mean one has a better grasp of things than an expert. You could take me to a battle in Afghanistan right now, and I would be at a complete loss--I don't know the language, the culture, the history, or the significance of what I'm seeing.
Now I hear it all the time, from NPR to cable news channels. It's now a common phrase for a realistic, man on the street version of things. And so, a new phrase is born. Sigh.