Does the new Android Material Design support old version of android such as 3.0 or 2.1? if it supports how would it look like? as a real material design or just as old design? I am about to update my app with material design theme so is there anybody who already has done this?
As far as material design as a concept goes, yes you can do it all today. Some aspects of it would require a lot more work on your part (for example, imitating the new action bar design guidelines), whereas some parts are a lot more simple (e.g. the new guidelines for content spacing and colors).
There are also some libraries available to help you with this. There are many third party libraries out there that support the concept of "cards" such as Cards UI for Android and Cardslilb, and there is a library for the Floating Action Button.
As far as the Material theme goes for more or less automatically making your app "Material," no, there is no support library implementation available right now. What you see on the market at the moment is mostly done from scratch. I recommended holding off until Android L is officially released. The new versions of the support libraries will include support for at least some of this functionality (such as