I'm a bit confused. It doesn't seem like this is very "lorem ipsum". Lorem ipsum looks like actual text, whereas, this does not look like actual image content (due to most images not being solid gray). To my mind, a better lorem ipsum image would have a variety of colors, shading, textures (which is probably why Lenna is a popular choice). This way you could see how a variety of image colors work with your design, color scheme, etc.

If this is simply for formatting placeholders while designing web pages, wouldn't <span style="width: xxx; height: yyy; background-color: grey; border: 1px solid black;"></span> be a pretty easy workaround, and a lot easier on the network bandwidth?