While IBM is huge Open Source backer, when it comes to a legacy piece of their own proprietary code, Open Source apparently isn't an option.

OS/2 backers have sent a petition to IBM (actually their second such petition in the last few years) to get OS/2 open sourced. IBM isn't biting.

As stated in our response to your September 2005 letter we have considered the positioning of OS/2 and open source several times in the past, and for a variety of business, technical, and legal reasons we have decided to not pursue any OS/2 open source projects.

IBM has service offerings that continue to be available for customers who need ongoing support for OS/2, although IBM has no plans for product enhancements.

Though it may seems like a long time since OS/2 was a viable option, it really hasn't been that long.  It was only two years ago that IBM officially (and finally) pulled OS/2 from the market. At the time IBM noted that they would continue standard support until December 31 2006 and, beyond that as a separate Service Extension fee-based offering.

How much IBM still makes from those OS/2 service contracts is unknown.

IBM since 1999 however has puts its bets on Linux and on its own AIX Unix OS. If an open source OS/2 were to emerge who is to say that developers could improve it and make a third choice?