Since then, Ubuntu has done some very questionable things. Canonical, the company behind them, claims they are trying to make the experience as seamless as possible for people unfamiliar with Linux. Noble goal. Puppy Linux is the same. However, no one complains about Puppy, and everyone complains about Ubuntu. Why? First, Ubuntu started incorporating Mono into things and didn't blink as the GNOME desktop started leaning on it more and more. Their insistence at embracing Mono was bad enough. Then, Ubuntu changed its community agreement to enable what is called "open core". For the uninitiated, open core is a bastardization of Open Source. You can look at and tinker with it, but all rights revert to the copyright holder, meaning they can stop you from doing something they don't like. M$ came up with open core, hoping to get Open Source nuts without surrendering anything. No one's buying it. Canonical has yet to do anything with it, but the fact that the agreement includes a provision covering open core...lawyers don't draft something if they don't intend to use it. Lots of people have become very leery of Ubuntu.
With tablets and phones getting Android, Ubuntu has decided to make a change. With the 11.04 release of Ubuntu, the desktop will change to UNITY. UNITY is a rework of GNOME, intended for tablets. It's obvious where this is going -- people get used to the interface on tablets and have no trouble transitioning to a desktop environment. Dell is helping back the work to make UNITY (cell phone environment, meaning one foreground app at a time, that won't work in today's desktop environment) ready for the desktop.\
So it's not completely abandoning Mono. And I'm sorry, but the desktop under Linux isn't actually that tough. They are hoping for association. I see a company more interested in carving its own identity than upholding the community.