In a mature IT market, it becomes hard to make any significant changes in hardware architecture or software design without upsetting the installed base of legacy users.
This, of course, makes the evolution of a product somewhat troublesome. Change must fit within the strict confines of compatibility, ensuring both hardware and software vendors do something useful without upsetting the entire apple cart in the data center - or on our desks and in our laps.
To be sure, this is a lot less exciting than having a totally new thing come along, as proprietary minis did in the late 1970s, commercialized Unix did in the mid-1980s, and a decent Windows operating system for desktops and Linux for supercomputers and then regular servers did in the mid-1990s.
These kinds of tectonic shifts are very difficult to imagine in operating systems these days, thanks to the internet where no one particular machine or its operating system is the center of gravity for users and developers.
That is not to say that there isn't a lot of underlying infrastructure in operating systems that cannot be and must be improved. Just to take one example, the advent and mainstreaming of virtual machine hypervisors for Linux and Windows boxes in recent years is about gaining efficiencies in the data centers.
Hypervisors allow for sophisticated, flexible, and efficient distributed computing by cramming many virtual machines and their workloads onto a single physical server. They don't, though, change the nature of computing all that much.
Similarly, network connectivity for servers, desktops, laptops, and other devices is a key attribute of any operating system these days. A lot of work has gone into making wireless and other network connectivity easier for personal devices and server operating systems have been tweaked with improved networking stacks to take advantage of the fastest network gear the industry can deliver.
If there is one prevailing thing that all kinds of end users desire, whether they are in the data center, in cubicles, or at home: They want operating systems that are easier to use. And operating system makers - be they commercial entities or open source software projects - are all trying to do that with better user interfaces, more graphical tools, and automation wherever possible.
Think of how much easier it is to link to a wireless network in Linux today than it was only a few years ago, just as an example.
Given where we are in terms of market maturity and the work that remains to be done, it's worth looking back at 2008 to measure what really changed in the world of operating systems. Also, it pays to look ahead at what vendors have lined up for us in the coming twelve months.