One thing to remember is Xbox Live members have to pay for the Gold membership while the PlayStation Network is totally free. That is one reason for its growing popularity.
"Sony also announced that over 380 million pieces of content have been downloaded, generating revenue in excess of $180 million since launch."
The Sony registration numbers refer to PSN registrations which represent lifetime-to-date PSN registrations on PS3s (possibly PS3 forum registrations as well), PSPs and through PCs while the Xbox Live numbers are active accounts only.
Microsoft recently stated that Xbox Live revenue has exceeded $1 billion.