No, Linux hasn't caught an illness. Mono is the development platform Friedman used to build Dashboard. Eric Dasque, the Senior Project Manager for Mono with Novell, took a moment to explain what Mono is and why it's important. Mono is the Linux implementation of the .NET programming standard Microsoft placed under the control of the EMCA--yes, Dasque pointed out time and time again that people are always trying to tell him .NET isn't a standard, but that in fact .NET really is a standard.
Dasque and the Mono team want to attract more programmers to Linux, and not just the serious geek crowd. It's the Independent Software Vendors they're aiming at, often the types of folks that want to build vertical market applications like pet shop management utilities. These people are used to working in user-friendly environments such as Visual Basic, and increasingly in .NET.