The acquisition of the security software outfit bolsters a product suite designed to loosen Microsoft's hold on business customers.

Google has long coveted the pot of gold represented by Microsoft's business customers, those lucrative users of such applications as Outlook e-mail, Excel spreadsheets, and PowerPoint slide presentations.

In recent years, Google has been snapping up companies in hopes of replicating that suite of services, and it finally may be nearing a full quiver.

On July 9, Google said it is paying $625 million for security company Postini, which helps corporations and smaller businesses monitor e-mails and instant messages, encrypt information, and enforce company policies in such areas as the dissemination of confidential information. Google's third-largest purchase after YouTube and DoubleClick, Postini is the market leader in its field, with more than 36,000 companies using its products.

"With this transaction, we're reinforcing our commitment to delivering compelling hosted applications to businesses of all sizes. With the addition of Postini, our apps are not just simple and appealing to users -- they can also streamline the complex information security mandates within these organizations," said Eric Schmidt, Chairman of the Board and Chief Executive Officer of Google.

Hosted services, like Google Apps and Postini solutions, provide organizations with high quality communications tools without the expense and hassle of traditional on-premise solutions. Google Apps, which includes Gmail, Calendar, Talk, Docs & Spreadsheets, and Personal Start Page, has been adopted by more than 100,000 businesses already. Postini solutions include Email Security, IM Security, Web Security, Message Archiving, Message Encryption, and Policy-enforced TLS.