Here is a radical suggestion to fund the development of newly-emergent open source OS platforms: Keep the platform and as much of the other software on it free. Sell the development tools.
The term "development tools" would mean the environments created by the platform's developers to develop software for the platform, device drivers for it, and the platform itself. One could even envision a unified virtual-machine execution environment and step-debugger, where the OS (and its apps) could be run in a VM and interactively tested.
This wouldn't have to be a one-size-fits-all solution. One could buy a basic development app for one price, add in other modules as needed, or get the whole thing for a bit of a discount. (Not everyone would need the driver development kit, for instance, but I imagine the interactive debugger would be massively popular.)
Much of my thinking in this vein materialized after reading about the progress of Haiku OS. Development of a project like that needs to be funded in some way for the best long-term results. So rather than charge for the platform, or access to the platform, why not charge (if only nominally) for the privilege to write the best possible software for the platform?
This isn't to say that free tools wouldn't be available for the platform in question. It'd be impossible to prevent that, anyway, and there are plenty of programmers not obsessed with the latest-and-greatest tools who can do yeoman work with whatever's lying around.
But there are still plenty of programmers serious enough about their work to pay top dollar for the best tools to get the job done. Sell those tools to the people most serious about making your platform as good as it can possibly be, and they'll take you seriously in return.
InformationWeek has published an in-depth report on Sun's future under Oracle. Download the report here (registration required).