Do you plan to implement support for Retina MacBook Pros? This will make the application look nice on Retina displays. Thanks!
Retina display images are basically 4 times larger filesize. To implement that the non-retina users get sent the same larger resolution images, but without any benefit and at the cost of longer download times.
There are alternatives, the developers could implement browser detection so only retina users get the larger images. In that case the web designers then need to create and upload 2 versions of each image (again there's a more technical approach, have the webserver downscale the retina image before sending to non-retina users).
Apple internet connected devices may account for as much as 20% of users. Only a few of those have Retina displays.
It makes poor business sense to invest in a technology that will only benefit a tiny minority of users and either increases complexity and cost or delivers a poorer service to the overwhelming majority of users.
Retina enabled web sites only makes sense for Apple themselves and people with products and services specifically targeted to Retina users.
I guess I should add something. Retina display is the terminology used by Apple to make it sound like they are doing something special and innovative. They aren't, there are internet devices from other manufacturers with similarly high resolution display capabilities. High res screens are more costly which will act as a drag on sales but if high-res screens do start to represent a sufficient market share then it will indeed become realistic to consider web site upgrades.
This isn't on the immediate agenda I'm afraid - it's still pretty difficult to achieve this and not currently worth the trouble considering the small percentage of users that have retina displays.