Thomas Claburn at InformationWeek - Google Revealed: The IT Strategy That Makes It Work:

"Lots of small, short-lived projects mean traditional project management software based on task lists isn't right for Google. For one thing, techies aren't very good at cataloging how they spend their hours. What they are good at, it turns out, is writing up a few short sentences or snippets about what they do each day. Those get compiled in a database along with periodic updates from project leaders about a team's deliverables. The project system tags the input by topic and routes to the appropriate people. "This is not hard AI," Merrill says. Still, who else manages workers like this?"