He wouldn't give me any specifics at all, but I can tell you that the challenge was related to the extremely low tolerance for lag on a search result page that's treated as law company-wide. He had to do it without slowing down the search page AT ALL, for anybody. Check it out; it even works on mobile.
It's not for common users. It's for people who want to pay for this service. Developers will build federation out to Twitter to reach those who don't want to participate.
That doesn't have to happen. Even though the conversation has barely begun, most of the people who are behind this are already concentrating on federation with Twitter. That's how the reach problem will be solved.
Key points from interview with Google engineering director Peter Magnusson during Google I/O. He explained their cloud direction. He insists that the future is toward completely managed services. Do you think so?
I see what you mean. But at that time, Google results weren't tied to personal identities, which had no clear definition yet, and that's what this whole Google+ project has been about.
But here's the thing: this actually lifts the lid on the echo chamber to be more open than it was yesterday. Google recognizes that global search is a necessary option. Before this update, it looked like G+ was just going to be rammed down every Google user's throat. Now we can opt out without having to log out!