I can't imagine enterprise level organisations allowing Google to Earn money via advertising.
I'm not entirely certain what you mean by this. I would take you literally, but taking that sentence literally would be mad (Google does earn money via advertising, and every enterprise-level organization "allows" it in the sense that they don't explicitly "disallow" it (what would that look like, anyway?)). Could you clarify?
I know that Google have made some efforts to make money by directly charging Enterprises but that represents a tiny part of their revenue to date.
In other words, is Wave a much smaller opportunity than they had hoped? And if so, it might just end up being a "side project"...