This site certainly has seen it's share of hosting environments. It started on a shared hosting, without even a proper domain name, then later moved among many of the popular virtualization techniques, first VMware server, then KVM and finally Xen (VPS). But, most of that time, it somehow wanted to end on a real hardware, to have a room to breathe, so to say. As my page on the subject of the digg effect clearly shows, there are times when load on the web server increases rapidly, and to survive such sudden rise in interest, it's best to be hosted on a proper dedicated server. Also I remember that the ever popular picture of Linus Torvalds giving thumbs up to Windows 7 OS ate a fair amount of bandwidth in short time.
The problem is, dedicated servers can get really pricey, because you're leasing not only the physical hardware, you also expect the server to be in a properly air-conditioned and secured data center, connected to UPS, have a good network connection and you also expect the hosting company to pay for all those electricity, cooling and networking bills for you. And of course to install the OS for you and to quickly replace any malfunctioning part etc... All this quickly adds up and pricing goes through the roof fast, thus making most of the real (enterprise) servers completely out of the reach from hobby projects like this site. Fortunately, in the last few years, there has been a steady growing market of so called green servers, small and affordable units that are more energy efficient, possibly more densely packed and certainly more affordable, but still giving great performance to those for whom the absolute availability is not the first priority.