Chris, PRS, keep in mind that the only thing that stops sound is MASS - 1/4 ply will attenuate high frequencies some, but do nothing for lows. Serious sound proofing requires two leaves of mass, separated by air and insulation - ideally this would be two completely independent shells 360 degrees around your space, separated by air and insulation. In actuality, this isn't possible without anti-gravity machines, but you can get close - just not in an apartment.
The dividers you show are referred to as "gobo's", which is a contraction of "go between" - they will change the acoustics inside a room, depending on where you put them - what they will NOT do is reduce the amount of sound getting into or out of that room.
If you can ignore the sales hype, go here
http://www.auralex.com/category_max-wall/category_max-wall.asp
and click on the picture over MAX-Wall 831 - it will show a better idea of what you could do with your three-panel wall.
Keep in mind that all that foam will take out most of the higher frequencies, which you'll make even worse if you add carpeting. Carpeting ONLY kills highs, and for good sound you need EVEN absorption. Even the foam won't go low enough in absorption frequency to do that, but it will probably sound better than the bare room - the panels will also take care of flutter echoes caused by your parallel walls.
They may, however, make the flutter caused by your floor and ceiling (being parallel) show up clearer. If so, you could make another panel that lays across the tops of your 3-panel divider (see the pic on the auralex site again) - if you were to put extenders on the ends of the panels that are away from the center one, your overhead panel would not be level and it should finish the job of killing any flutter.
Remember, all of this will probably make less than 2 dB difference in sound proofing, although maybe more if higher frequency traffic noise is part of your problem (while the foam is killing YOUR highs, it should also kill some of THEIR highs :=)
Gotta run for now, see if any of this made sense... Steve