Google has released WebP, a lossy image format based on the image encoding used by VP8 (the video codec used in Google’s WebM video format) to compress keyframes. According to the FAQ, WebP achieves an average 39% more compression than JPEG and JPEG 2000 while maintaining image quality. A gallery on the WebP homepage has a selection of images which compare the original JPEG image with the WebP encoded image shown as a PNG. There’s no information available yet on which browsers will support the WebP image format, but I imagine it will be all the browsers which currently have native WebM support — Firefox, Chrome, and Opera.