I'm not sure if there is a word for this type of image layout, but it's pretty common - one large image to the left, with two smaller images tiled vertically to the right, like an old window.
I needed to show a client some different options for image sizes, so I put this calculator together quickly to show some examples.
The images come from the excellent Lorem Pixel, and the slideshow uses the jQuery cycle plugin.
Containing rectangle
680 x 390px
Large left image
336 x 390px
Small right images
336 x 191px