Google and postini

Google recently announced their acquisition of Postini, a company that provides hosted email security. Though it seems to be a very positive move for corporates planning on Google Apps , I am not very much convinced that Google can improve security by acquisitions. You cannot buy something and add it to your stack and claim to be secure. Security has to be layered. I mean Security has to be layered. If you are running a web application, your application code, the server (web / App / DB / Media / watever) on which it is deployed, the Operation System on which the server runs and the HW on which the OS is installed and the Network on which this whole system is setup, all have to be secure. Only then you could achieve a better score in security. I am sure Google is aware of this and is strengthening security on all their layers. I hope Google is not on a shopping spree for boosting their shares