Who innovate today in desktop experience?
This is a complex question…
Google is the first who come in my mind. A lot of engineer have left Microsoft to Google. Google have make a lot of new things as Google hearth, Google Desktop, Gmail, Google reader, Igoogle, Gcalendar , Google spreadsheet,… But Google video was a badtrip and they have to buy Youtube. Google have nothing really new since few month… Google have done a great job to make a web “Office” but it is just a migration to web not a real new idea.
EDIT: they have just released the google presentation.
MAC OS X have add a lot of new idea in desktop but nothing new since it.Apple have take a strong leadership in mp3 reader and Iphone will be a success. So, Apple is now clearly investing in Iphone, Ipod which bring more money to them.
The big one, Microsoft, fall down. The OpenXML have been refused by International Organization for Standardization.Windows Vista is compare to the Windows Me and Microsoft have provide a downgrade to Win XP.

And Aero is not as good as compiz. Microsoft is good to copy something and make it better for everyone (MACOS->Windows, Lotus 1-2-3-> MS Excel, Java->.NET,…). But Microsoft is in bad way. MS Office and MS Windows are the products which bring cash to Microsoft. MS office is challenged by openOffice, Google spreadsheet,… And MS Windows is left for Linux on server side. and now the last part (but bigger one) desktop environment is more and more challenged by Untubu & Suse who have simplified Linux to make it usable for everyone.
Innovation come from open source today. Power of community get bigger!
The console is left for beautiful GUI on linux. Microsoft have seen the trap and contract with Novell to save him for future but revolution come fast and who know what will be the future market-share of desktop?
Imo, It will take time.I am switching to Linux as many other people. I am an engineer and for moment most of people who switch to Linux are IT engineer but they are prescriptor. When someone want to buy a computer and know nothing about it, he ask for advice to prescriptor. The other sign is that administration switch to Linux. A lot of project improve compatibility (Mono, Moonlight, cygwin…) and other products are on both plate-form (OpenOffice, Firefox,…). So all this things make migration easier but a lot of issue is still there because of the lack of support for Linux.