I'm not sure about the responsive image format thing. The problem is : the restrictions of mobile today (both in term of dpi and in term of connection speed) ar

I'm not sure about the responsive image format thing. The problem is : the restrictions of mobile today (both in term of dpi and in term of connection speed) are likely to change very quickly. This means we'll need to re-encode images as mobile devices change. A server-side solution where you store the full resolution image only and then use a cache for lower resolution seems much more flexible.