Google seems to be integrating all of its products with the single google account.

Just noticed one peculiar advantage: Using a single google account, now one can login two or more blogs simultaneously. No need to memorize separate usernames and passwords. Also one can quickly switch over to other google products like Gmail, Orkut, Gtalk etc...

On othe other side, there should be a concern about security issues. Suppose the google account gets hacked, all the services of google products used by the person, are exposed. In this case I think having separate login accounts seems safer.