Mark Shuttleworth, the founder of the Ubuntu project reckons that Linux and (specifically) ubuntu should be made prettier. I have to agree!
As far as I can see (and feel free to disagree with me) the Mac has only two things over Linux; Looks and usability. Ubuntu has already tacked usability to a huge degree. Practically everything can be done via a GUI if you wish. Now they’re turning to looks. The new cutting-edge version of Ubuntu, Edgy, has a new boot screen which looks quite good and the login screen is also quite attractive. I think the actual Ubuntu desktop also looks pretty great by default, but the plan is to integrate XGL or AIGLX onto the desktop by default to give 3D effects, better graphics and improved desktop usability.
As for Windows, the only thing Windows will soon have over Linux is software compatibility - a big problem to overcome I agree, but the statistics for people on Mac and Linux platforms (by percentage) appears to be growing steadily.
So now the only thing left is marketing…