We've all put so much work into our blogs, and I'm sure you'd hate to see all that hard work just disappear. Unfortunately, there are some people who would get rid of all that, either because they think it would be fun, or because they want to spam your site to push some terrible product that they wouldn't be able to advertise any other way.
One very common complaint from new users to Ubuntu is the ugly brown default theme. It seems to give them a bad first impression of the operating system, based on how it looks at first. But now they've come up with a completely new design, which makes the brown look like a beautiful photo of autumn foliage.
Scalable Vector Graphics, or SVG, is a standard for a type of XML used to describe an image. There is an infinite number of possibilities with this, allowing you to create just about any image with it.
The image you see on the left was created using SVG. It is normally 93x93px in size, but it is scaled up to 150x150px, without the image quality suffering.