Google will deepen its online business service suite as a result of its purchase of Postini, a provider of message security, encryption, and policy enforcement. This looks to be reinforcement for Google’s move into business service, giving it a new major revenue source beyond advertising.

The all-cash buyout will give Google entree to corporates already signed with Postini, as well as more tools in its bag for its challenge to Microsoft in the online business service arena. Already, Pixar favors Google over Microsoft to replace internal services.

One virtue of such an approach to businesses is that spam, spim, and objectionable content never reach the business’s Internet feed, which multiplies the effectiveness of existing broadband connections. Current Gmail users will also favor such an approach, as per an ESG analyst.

A Google blog from last year describes their Google Apps beta last year, and Google Apps offers a thirty-day free trial to help wean companies from reliance on Redmond’s offerings.

Is your firm considering replacing on-premises apps running on your servers with on-line applications hosted by a provider, Google or otherwise? What are the major pitfalls of such an arrangement? Join the discussion.