title_body: How well is SVG (being a "pixel image" alternative) supported? I didn't mention it in my previous question because it's an image format made of vectors, but would SVG provide a usable alternative for non-pixel images like illustrations? 
  
  If, how well is SVG supported by the mass of ebook readers… and is that support dependent on specific ebook formats? (Not including TXT as it's obvious you can't embed SVG into that.)
upvoted_answer: As Donald points out in his answer, (new) devices would have to support SVG 'images' as support for SVG is specified in the EPUB 3.0 standard.
  
  For line drawings, but also for zoomable images (maps come to mind), this is a vastly superior format over any pixel based file format.
  
  How soon that adaptation will happen will be influenced by how easy it is to adapt the various rendering engines used in the devices. Some of the features of 3.0 require more processing power, potentially reducing battery life even if not actively used. 
  
  Conversion to non-EPUB formats of EPUB 3.0 with SVG is going to be more difficult, some will not support it at all (which would require rendering in some pixel based format at some resolution), conversion to others formats (PDF) would become more complex than the current text and image conversion.