Blobfisk, I believe there are two flavors of SVG. One depends upon browser based plugins to work - like Adobe's. The second flavor generates SVG server-side as with PHP's GD module. A little code and you can create images on the fly - really cool.
As for penetration I don't know for sure. While it's not overly difficult to use SVG, it is limited to vector graphics (great for engineering drawings, charts, graphs, etc..) hence the name Scalable Vector Graphics. So I think it hasn't really come of age yet. But it will.
I've had a look at the Adobe SVG and I liked what I saw. And I agree that it's full use and potential is yet to be seen. I've not yet had a reason to use it, but at least it's there as an nice option should that need arise.
Thanks for the link and allowing us to (try) and keep abreast (if not slightly ahead) with what's here and coming.