Sun's President and Chief Operating Officer, Jonathan Schwartz, yesterday published an Open Letter to the CEO of IBM, Sam Palmisano, in which he alluded to "behavior... reminiscent of an IBM history many CIOs would like to forget" - a reference to Sun's frustration that IBM isn't supporting Solaris 10 with WebSphere, DB2, Tivoli, Rational and MQSeries products.

In his "Dear Sam" letter - circulated via his blog - Schwartz refers first to the "long history of partnering" between Sun and IBM ("We've worked on Java together, more recently you joined us in the Liberty Alliance") then grasps the nettle:

"We've repeatedly passed along customer interest in having IBM support Solaris 10 with WebSphere, DB2, Tivoli, Rational and MQSeries products...[T]hey'd like the choice to run IBM products on Solaris 10, and they're feeling that your withholding support is part of a vendor lock-in strategy. A strategy to trap them into IBM's proprietary Power5 platform only."

"We've made Solaris into a truly vendor neutral OS," he adds, saying that Sun's customers and partners "love that we're open sourcing Solaris, and that we'll be the first open source vendor to offer a commercial version of our product with indemnification against intellectual property lawsuits."

Sun customers have made repeated calls to IBM, Schwartz claims, about having the choice to run IBM products on Solaris 10.

"We've made sure your engineers know that moving from Solaris 8 or 9 to Solaris 10 takes no work, given that we offer true binary compatibility. If you're on SPARC, and you'd like to take advantage of a world of x86 systems, it's a simple recompile. There's no recoding at all. Same applies to scaling up from Intel or Opteron to SPARC. No recoding. So the technology is there, and so are the customers, partners and opportunities."

On a more upbeat note, he then offers Palmisano his call to action: "We stand at the ready to help you tear down this wall."