Having the possibilty to upload a higher resolution image for retina displays while still retaining original description etc. would be very usefull. Colorbox i.e. already supports retina images.
Also, having the option to serve different sized images for specific resolution displays is something that would be useful for responsive layouts. Something like the Hammy plugin for WordPress galleries for instance.
I would like to know whether there are plans to make NextGEN Gallery support retina images and responsive design in the near future so I can decide whether I should stick to the native WP gallery or not. Thanks in advance.