Solid is the new hardware device framework for KDE 4 that features, among other things, a hardware discovery layer which allows you to detect and use devices regardless of operating system or architecture. You can learn more about the Solid project at solid.kde.org.
For a more detailed (still not complete!) description, read here.
This tutorial is written for developers looking to use the Solid hardware discovery layer within their applications. It can also serve as a good starting point for developers looking to start working on the Solid framework.