Privacy considerations will be very present again, as Google is bundling the different logins for its applications into a new part of their eco-system: Google Profile. It provides a way for the customers to have to maintain one profile, and be able to link from some, but in the future all, Google products.
I can see the reason for this in a service like Blogger, where your profile could be important when you post responses to a certain post, but I’m not sure about the rest of the services. Sometimes, I don’t want people to see my email, so I don’t give it. When you have it in your profile, it might prove difficult to segment what information you want to provide to whom.