Well, the .357 Sig was an attempt to replicate the ballistics of a 4" .357 Mag revolver in an autoloader. And with bullet weights up to 125 gr., it actually does a pretty good job of it. The Magnum pulls ahead pretty quickly when you start looking at heavier bullets, and I don't know that there are really any factory loads that go any heavier than 125 gr. anyway. But that bullet weight at those velocities is nothing to sneeze at, no matter what cartridge is pushing it.
Having said that, the Desert Eagle in your picture appears to be the lightweight L5 model. It's actually got a 5" barrel, not the 6" barrel of the full sized MK-XIX Desert Eagle. And the porting at the end of the barrel effectively reduces the rifled length by another inch. So you actually have a fairly straight-up comparison between the 4" Glock barrel and the effective 4" DE barrel.
I usually load 158 gr. bullets in .357 Mag, but I've shot some of the 125s over the chronograph. For comparison, my 125 loads using AA#9 give me around 1380 fps. from the L5, where some 125 gr. Winchester ammo was running 1450 fps. in one barrel in the 6" gun, and 1515 fps. in another. Not the same ammo, but it gives you some idea. Federal 158 gr. JSP does 1268 fps. from my L5, and 1405 fps. from the full-sized gun. Depending on what powder I'm using, I get a 200 to 300 fps. increase in the 6" gun vs. the L5.
The only .357 Sig ammo I've shot over the chronograph is some Sig brand 125 gr. FMJ, which averaged 1410 fps. from a Glock 22 with a .357 Sig conversion barrel.
So yes - for heavy bullets the Magnum is still on top. But for 125 gr. self defense loads, the .357 Sig is going to do pretty much the same thing, but with less blast and recoil.