Reading the Compatibility section of Android L Developer Preview (http://developer.android.com/preview/material/compatibility.html) I\'ve seen that i can create an APP using
This has changed since the original answer, as Google released better support for Material design in the AppCompat libraries (which support mostly all versions of Android).
At this point, you should be using these libraries for all development, then you will be able to support Material design related features in all your apps.
Here is how to set it up: https://developer.android.com/topic/libraries/support-library/setup.html