Private clouds are where most corporations will find the most value, and for that they need off-the-shelf operating systems to do the heavy lifting for them. At the moment, cloud computing means purchasing time, space and bandwidth for specially-created apps from a third-party provider that may or may not be trustworthy and may be required to hand over data to some untrustworthy government depending on where the cloud service data centre is hosted. To avoid those uncertainties and hassles, large companies will seek to turn their own data centres into flexible clouds, which means they need a server operating system built for such a thing. If the purpose of such a cloud is to run virtual Windows servers, then it won't much matter whether the underlying OS is Linux-based, so I can imagine that being the first place such a product will come from.
Converting will still be a pain, since you'd have to keep all your existing servers online while you switch, but imagine being able to add a new server to a data centre, install an off-the-shelf operating system and entering a few configuration parameters, then it goes and adds itself to the cloud of local machines, including sharing its storage, offering its CPU for new threads and its RAM for direct addressing. Whenever another machine dies, all the storage is already backed up onto other machines and whatever processes it was running can be resumed on other CPUs in other RAM. That's the power of cloud computing without the dangers.
Mokalus of Borg
PS - Cloud computing is getting a lot of hype.
PPS - But there are also some problems.