Google integrates Orkut–and #of users starts to matter as engagement metrics rise

So I wonder where Google is going with Orkut ? Last night, I got an email asking me to merge my (long-unused) Orkut log in with one of my Google sign-ins.
I logged into Orkut, made the change, and started thinking about how counting registered users–not just page views–is probably going to become more important to Google as they build their advertising products–and then need to demonstrate additional forms of growth to the market. Registered users and engagement metrics are both criteria that have never matter much to Google–but now, with the rise of MySpace and the amazing engagement metrics it demonstrated–and the shift toward AJAX-ed pages that reload less often, thereby depressing page views, Google seems likely to join the pack counting audience and engagement along with other stats.
Registrations and time spent seem like especially important metrics given the Big G’s recent acquisition of YouTube–If I worked at Google, I would be thinking hard about why and how I could integrate aspects of Orkut and YouTube to development and demonstrate social media metrics and growth that would impress the street and scare my competition.