Good is hard. When I left O'Reilly Media in 2005 we were just ending a period where many programmers worked with a set of physical O'Reilly books on their shelf. And everyone at O'Reilly could see that their business was being eaten away by free. Stack Overflow didn't exist yet but we could feel it coming. At the time, we hoped that UGC would have some sort of wisdom of the crowd thing that would lead to high quality…
The problem is that "timely" bit.
A good book take 3-6 months to write, edit, review, and publish.
In that time we could have as many releases with the info in the book radically out of date.
Only solution is to go online, but that doesn't help the traditional write/edit/review cycle much.
Things change so fast, I don't see much option to Stack Overflow... Not really.