Didn't they try this with HP web OS. That failed I wouldn't put money on this.
That said, this isn't the same as WebOS. WebOS ran javascript apps, but they ran on the device itself. From what I can gather, B2G is running everything on the actual web. It's very different.
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Edit: I may have been wrong there. Apparently it is running locally. This quote from the web page through me off:
"You don't have to pay the penalty of a big smart phone operating system if you're running directly on the web"
That's a bit misleading.