I just finished first version of webp-ffi. For now it support encode png, jpg or tiff image to webp (with options, like quality, resize, crop) and decode to png.

WebP is a new image format that provides lossless and lossy compression for images on the web. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller in size compared to JPEG images at equivalent SSIM index. WebP supports lossless transparency (also known as alpha channel) with just 22% additional bytes. Transparency is also supported with lossy compression and typically provides 3x smaller file sizes compared to PNG when lossy compression is acceptable for the red/green/blue color channels.

You can see example of images here. For now only Google Chrome and Opera browsers support this format of images.