As you're well aware, there are lots of JPEG and PNG optimizers and encoders, both lossy and lossless. However, newer image formats like webp and JPEG-XR each have only one reference encoder, from Google and Microsoft, respectively, and no GUI tools for working with these formats.
Do the webp and JPEG-XR formats have the sort of headroom for optimization that JPEG and PNG do? Is there anything about the formats that has prevented the emergence of third-party encoders and optimizers? Have any of you looked at building new encoders or optimizers?