Paul Hopgood's SVG-Editor is available at the SVG-Editor site.
SVG-Editor is not a drawing package with the exporting of SVG documents added as an after-thought. Rather, SVG-Editor is designed explicitly as a tool for SVG developers wishing to draw or modify SVG documents with precise control over the content of the resulting SVG document.
SVG-Editor uses a browser's native SVG renderer (or Adobe SVG-Viewer with IE 8) so it is a true WYSIWYG (bugs 'n' all) editor.
Features not currently supported by SVG-Editor will be preserved in an edited document but this is a long-term project which will have more sophisticated features added as time goes by.