Google have made available WebP, as a replacement for the JPEG image format. Google claim that WebP, which uses algorithms from the VP8 video format , better looking images that can help make the web faster.This format does have the advantage of being free from patent issue, but I don;t think the increased efficiency makes it worth changing to. According to "Google Promotes Replacement for JPEG Image Format" (Mark Hachman, PC Magazine, 09.30.2010), the new format is on average 39% more efficient than JPEG. From my observation of JPEG images in web pages the problem is not efficiency of compression but the wrong images at the wrong resolution being used. Typically images are scanned at a far higher resolution than needed, making the files tens or hundreds of times larger than needed. Monochrome images are stored in colour format and line drawings, which should be in GIF or PNG, are stored instead in JPEG.
If Google wants to speed up the web, then a tool which helps people scan images in the correct format would be useful. Also they could provide web-masters with a tool which reports images on their web sites in the wrong format and duplicated copies of images (the Australian Government stores millions of copies of the Commonwealth Arms, for example). It would also help, particularly with mobile clients, to stop the download of progressive format images when sufficient detail had been provided.