I've also added a couple new windows archives with Windows Imaging Component (WIC) support disabled as we're still missing full metadata support on that side. These 'non-wic' builds have feature parity with Linux and Mac.
* improved gif2webp tool
* numerous fixes, compression improvement and speed-up
* dither option added to decoder (dwebp -dither 50 ...)
* improved multi-threaded modes (-mt option)
* improved filtering strength determination
* New function: WebPMuxGetCanvasSize
* BMP and TIFF format output added to 'dwebp'
* Significant memory reduction for decoding lossy images with alpha.
* Intertwined decoding of RGB and alpha for a shorter
* WebPIterator has a new member 'has_alpha' denoting whether the frame
* Container spec amended with new 'blending method' for animation.
As a reminder downloads via google code are slated to be disabled on 1/15/2014 so I'll be making an announcement soon regarding the new location.