Sun Microsystems announced earlier this month that it will make the Solaris 10 version of Unix available free by the end of January. It is also planning to make the source code available.
The supplier is trying to take the purchase price and the open source rhetoric out of the buying process. Customers can then choose Solaris 10 rather than Linux for its performance and lower total cost of ownership, according to Sun.
What is happening is straightforward. After a decade of anti-Microsoft rhetoric, Sun has finally faced the fact that its real enemy is Red Hat, and it is changing its business model to compete. Instead of charging for the operating system, Sun will charge for support, with prices starting at $120 (£65) per CPU per year.
Of course, Linux has other attractions - the low cost of Intel servers and the potential to attract lots of useful applications. In future, most software will be written for Windows and/or Linux first, and ported to alternatives less often or never.
Sun is tackling the first problem by promoting its x86-compatible version of Solaris 10, targeting 64-bit AMD systems. It is tackling the second by enabling Solaris 10 to run Linux applications natively. This will allow big customers to join the Linux party without the risk of running it.
Sun has clearly compromised its strategy of vertical integration. Instead of pushing Sun Java and Sun Solaris running on Sun Sparc boxes, it will push Java and its Java Desktop System running on Solaris, Linux and probably Windows, on Sparc and x86 hardware.
It is not the horizontal integration that most of the IT industry adopted more than a decade ago, but it is as close as Sun can get at the moment. But it is hard to believe it will work. IBM has managed the trick of being "pro- Linux" while selling AIX directly against Linux, and while making practically all of its turnover from proprietary systems. However, it may prove harder to be "pro Linux" while selling Solaris against Red Hat Linux.
While it will be easier to sell x86 boxes at low prices, the benefits are not clear. Sun can match Dell on price, but not on volume, inventory turns, manufacturing efficiency or component buying - nor can anyone else in the PC industry. Sun could end up selling x86 servers at a loss instead of Sparc servers that make substantial profits.
But you only have to look at the momentum behind Intel/Linux to see why Sun is changing tack. If these changes are risky, the alternative looks worse. Perhaps the biggest question is whether Sun has left it too late.
Jack Schofield is computer editor of The Guardian