IBM Wednesday said it will consolidate nearly 4,000 PC servers onto mainframes running Linux in a move that will cut $250 million from the cost of operating its six major data centers.

IBM says the move will save enough energy to power a small town and will reduce by 85% the square footage needed to house racks of computers.

The company has 8 million square feet of data center space, which is the equivalent to 139 football fields. The U.S. sites targeted for server consolidation currently reside on approximately 184,000 square feet, according to IBM.

The company is trying to add yet another chapter to the life of the age old mainframe, which has been left for dead on the side of the information superhighway more than once.

And it is trying to make a statement about the future of distributed computing and IT infrastructure design by tapping into the mainframe’s scale, security and virtualization capabilities.

“There are all the altruistic aspects, but IBM is doing this to prove a point they have been trying to make for years,” says Dan Olds, principal of the Gabriel Consulting Group. “And that is you can run Linux apps, small apps, the non-traditional mainframe apps on the mainframe by the bushel load and that the usage model will pay off in terms of performance, security and economies related to people costs and facility costs.”

But Olds says to be successful IBM will have to win over the non-mainframe user.

“They have to get where a non-mainframe heritage guy, a Unix or x86 guy, is willing to take a look and take it seriously. That is what this is about.” He says IBM is being smart with this strategy in that they are converting their own data centers first, which will provide knowledge for IBM and credibility when trying to sell customers on the idea.

“IBM is going to be drinking its own champagne,” says Dave Anderson, System z green evangelist for IBM, who said the consolidation focuses on systems that run IBM’s business and support 350,000 users. “I think you will see the mainframe make a huge resurgence as people try and run their data centers most efficiently.”

IDC last week reported that the IBM mainframe posted its fifth consecutive quarter of revenue growth and outgrew Windows-based servers in 2006 in terms of revenue.