What does ‘shoe–leather journalism’ mean?

Solution 1:

The phrase is "shoe leather reporting".

I believe the meaning here is that genuine reporters will be out on the street walking, investigating, talking first-hand i.e. wearing out the leather of their shoes for a good quote or story. This is as opposed to new media where people pick up online research or data and pass it off as journalism.

My assumption turned out right, I've updated to include a reference

Part of the problem is that journalism terminology glorifies "shoe-leather reporting," whereby you pound the pavement so often you wear out the soles of your shoes.

Solution 2:

It more likely means basic or direct here, as the microbloggers described are not likely to be genuine news reporters of the old school, but simple de facto reporters who simply told what they saw. The "shoe leather" part refers to putting feet on pavement and going to get the story first-hand.