Wow, does this change really make fractional zoom work on touch devices? I'll check it out, interesting stuff!

I've taken a crack at this another way with a jsfiddle in the thread here: https://groups.google.com/forum/#!topic/leaflet-js/L4WRlqbvlzU

Feedback / improvements welcome.

See #1066 for some details on the firefox grid issue.

This patch is a great start, especially for pure GeoJSON maps, but by no means enough. I have extended it for my project:

1. Extended zoomIn and zoomOut functions in L.Map to use zoomStep
2. Extended _zoomIn and _zoomOut in L.Control.Zoom

There is probably more stuff I missed, but this allowed mouse zooming and zooming with + and - to work. If you are interested in my patch, I can put up a separate pull request.

Have there been any more developments on fractional zoom, especially for tile layers, implemented by resizing the tiles in CSS? Something like it is used for the zoom animations, but you can't stop at a fractional level. Is it just not practical in current browsers? I'm sure it's hairier than one might initially imagine, but I was thinking of taking a stab at it.

I would really like to use fractional zooming with leaflet. OpenLayers and Polymaps don't have a complete set of features like leaflet does. I would be willing to pay for someone to develop a plugin for fraction zooming.

I'd also like this to be made. I'm using Leaflet for image viewing, and I'd love to have the possibility to emulate the Rijskmuseum (they use Leaflet, but a very modified one, it seems?).
I need to fill the container with the image at load (cropping it if is of another proportion), but also being able to see the whole picture after zoomin out.
Nator's code is the closest to this that I've found, but lacks the filling container option.

Closing in favor of #2382

Change merged from #2382 is much more comprehensive, but it lacks the ability to support tile layers with support for fractional zoom.
I'll try and do a new PR for that.