Nomad in the space of 0's and 1's

Postini is a enterprise messaging solution which offloads concerns of message related attacks from the consuming enterprise. Postini provides security from viruses,spam, DoS, DHA (Directory Harvesting Attacks),phishing and objectionable content without any hardware or software commitment from enterprise's end. Postini is now completely acquired by Google for its google app premier edition and provides complete e mails, instant messaging management from google app panel. I find google spam filter reasonably good as I get almost 20 spams a day and like one odd in my inbox every 20 days, I wonder why google had to acquire postini and only two reasons come to my mind:
1> To increase google apps market by acquiring postini's customer base.
2> To launch google apps faster in enterprise market.
Also Its cool to have new technology from a new perspective (non googlish) coming in at regular intervals, Also google's infrastructure can do justice to any decent technology. Check out these two videos about postini and google message security for enterprise, one of them is a review ..

Please provide with links in comments if you have something to share about inner details of how postini provides these services :)