I finally found an SVG to XAML converter which just works, called ViewerSvg. It even supports offset rotation points (RenderTransformOrigin) which none of the other converters out there can handle.

The author is also very quick to fix any issues you have so if you want to have something fixed, just post him a mail.

It also comes with a 60 day evaluation version, so well worth a look:
http://www.ab4d.com/ViewerSvg.aspx

You can convert any printable stuff using the XPS printer from microsoft wich is nothing more than a zip file containing directly useable xaml

That only works for simple SVG files and in that case you better use InkScape.

For example, the output from the XPS printer doesn't contain RenderTransformOrigin so dynamic rotations will not display correctly. You can't blame it for that because this requires complex logic which converts transform-center to RenderTransformOrigin and Canvas coordinates, requiring bounding box calculations of all groups and node coordinates as well.