I was so tempted to start a similar thread myself...
What can I say this has been the first decade I have been really interested in fashion, buying my first (of many) copies of Vogue back in 2002. Thus I lack the ability to compare it to anyhting else, but suppose I see things with fresh eyes. Firstly I think fashion in its most basic form has moved on. Things are far skinnier (for better or for worse) glossy, and bordering on the technological. But there are a few key points in this decade which have very big significance.
The Business - As mentioned above I neither care nor appreciate it but its without question Ford and De Soles exit of the Gucci group was major. The two luxury goods giants LVMH and Gucci Group I think you could argue have summed up the business side of fashion this decade. With GG buying up Alexander McQueen, Stella McCartney, and Balenciaga and LVMH placing Marc Jacobs and John Galliano at the helm of Vuitton and Dior respictevely have had certainly the biggest impact.
The shows - the shows are now totally different, enormous blockbuster shows have taken place of the old fashioned salon style presentations. Also the politics of the front row have been an endless fascination for fashion enthusiasts.
The technology - Words can't begin to fathom the impact the internet has had on the way we consume fashion. From visualising it to purchasing it, its effect is undeniable. Now with the likes of McQueen and Guesquiere I think we may start to see this concept being put into clothing
The celebrity - One of the worst things to come out of the 00's in my opinion. Something I really hope we leave there too!