Not sure about this one google. Firstly, Worst. Name. Ever! Secondly, what kind of browser support do they think they'll get? I know ie is covered via google chrome frame but will Apple and Mozilla jump on this? Both issues have alloyed this one on me.
AFAIK Opera supports WebM, I assume they wouldn't have problem doing the same with WebP. IE and Safari might be a different story though, they wouldn't be so keen to support a format from their big competitor. If I would be in MS' shoes I would use that as an occasion to put a support for JPEG XR into Chrome/WebKit.
My boss walked passed and I called him over to tell him about WebP and he literally laughed out loud at the name. I said it without a hint of sarcasm and it was the first thing he noticed. Anecdotal I know; but still...
this reminds me of the internet's reaction to the name "iPad" - although I haven't heard anything along those lines since the first week it was announced.