IBM Introduces Two Open-Source-Only Mainframes in Hardware Push - Bloomberg Business

Also see Linux Foundation Launches Open Mainframe Project (TechCrunch)

"The new hardware will make it easier to run technology like the MongoDB database and the open-source software Spark, International Business Machines Corp. said. Spark is a free information-storing framework that IBM has said it is spending “hundreds of millions” to develop.
The mainframe is one of IBM’s signature hardware products that will help sell related software and services. Presently more than a third of IBM’s mainframe clients are running the Linux operating system, Tom Rosamilia, senior vice president of IBM Systems, said in a release."

IBM Introduces Two Open-Source-Only Mainframes in Hardware Push - Bloomberg Business