According to a post on Mashable by Jolie O'Dell, "Google is introducing a new format for images: WebP." O'Dell goes on to say:
Images on the web in this format will have smaller file sizes, load faster and relieve a lot of overclocked networks. They won’t necessarily look better — WebP images are as “glossy” as JPEGs — but the files might be around 40% smaller than JPEG files. [Read More]
If Google can convince browser manufacturers and Web designers to support this format this could be a big benefit to folks downloading graphics over cell connections, especially as carriers have been stepping away from unlimited service plans.