Expanding on Ray's comment above, this is really the compelling use case for WebP: a better container that does it all. Right now we have PNG, GIF and JPEG for three different use cases: animation, transparency and lossy encoding.
I can't easily pick and choose which of these I want, which means that we end up with 20MB GIFs that could easily be 1/5 the size, and crazy hacks to get lossy images working with transparency.
This is particularly painful for HTML5 gaming in my previous experience. For one of my projects that involved a giant, high-res game board with transparency (Nick's online Pai Sho), I ended up manually slicing the board up, converting center pieces to JPEG and leaving the edges in PNG. The images are all pasted together to make the final, seamless experience. What a PITA!
I can't easily pick and choose which of these I want, which means that we end up with 20MB GIFs that could easily be 1/5 the size, and crazy hacks to get lossy images working with transparency.
This is particularly painful for HTML5 gaming in my previous experience. For one of my projects that involved a giant, high-res game board with transparency (Nick's online Pai Sho), I ended up manually slicing the board up, converting center pieces to JPEG and leaving the edges in PNG. The images are all pasted together to make the final, seamless experience. What a PITA!