> it doesn’t even support all of JPEG’s features, let alone many of the much-wanted features JPEG was missing (alpha channel support, lossless support). It only supports 4:2:0 chroma subsampling, while JPEG can handle 4:2:2 and 4:4:4. Google doesn’t seem interested in adding any of these features either.

Wrong:

> We plan to add support for a transparency layer, also known as alpha channel in a future update.

from: http://googlecode.blogspot.com/2010/09/webp-new-image-format...