Does the jet blast from a large aircraft pose any risk for other aircraft nearby?
The airplanes in the photo are quite far apart, at least 1-2 lengths between each (it's just the long lens making them look cheek by jowl), and while in line going straight, they are only using a little over idle thrust to get rolling when required, so the jet blast effects are negligible.  The main factor is FOD (foreign object damage) kicked up, and at that distance that would mean sand/dust particles, but the effects of that would be too subtle to measure over the long term in any reasonably clean environment.  

That being said, if I was in a desert area where there was drifting sand on the taxiway, I would probably increase my spacing a bit behind the guy ahead.  And you can bet that the guy in the (what looks to be a) King Air that is second in line in the pic - walking with the elephants - is keeping a little bit more distance from the elephant in front as well, owing to the size differential. If I was in the King Air I would be worried about the plane adding a big shot of thrust in both engines to start the turn (hopefully they'll just use the left engine), and the inside engine would be pointing straight at me part way through the turn, and I would be staying  well back.   Airmanship and all that...