Expanding its security tools further, Google has acquired GreenBorder Technologies, maker of security tools that protect browsers, IM clients, and email clients.

So far, both GreenBorder and Google have been incredibly quiet about the terms of the acquisition. However, a message at GreenBorder's Web site says that while the company is no longer providing its tools to the public, it's still supporting existing customers.

California-based GreenBorder was founded in 2001, billing itself as a maker of "desktop DMZ software" for Windows. The company products use a form of virtualization to create a "sandbox" as a barrier between the OS and potentially dangerous content. In mid-2006, the company was putting the polish on its tools and openly invited the public to stress-test the products to help it find potential vulnerabilities in the tools.

Google recently launched its Online Security Blog, in which Panayiotis Mavrommatis and Niels Provos of Google's anti-malware team wrote that "online security is an important topic for Google." The company is currently evaluating the potential danger of the Web sites that it indexes.

"So far, we have investigated about 12 million suspicious URLs and found about 1 million that engage in drive-by downloads. In most cases, the web sites that infect your system with malware are not intentionally doing so and are often unaware that their web servers have been compromised," Mavrommatis and Provos reported in their blog entry.

Google hasn't said what it plans to do with GreenBorder's technology, however the technology does fit into Google anti-malware research activities and could possibly lead to new Google product releases.