Where is the new Linux experience?

Kelly McNeill writes "There has been discussion lately about the failure of Linux to make it in the desktop market. For all the work going on, things are still a mess for the average user, and there are only a few good usable applications. In the last five years, the desktop has made technical progress, yet still fails on a basic level -- the level of the average new user. Why is this happening, and what can be done about it?"