Take accessing contacts in android android.jar for versions 1.6 has People.CONTENT_URI for invoking contacts related info whereas in later versions we need to have api suppo
There's a nice article on android.com about it: http://developer.android.com/resources/articles/backward-compatibility.html
Personally I would suggest the wrapper class or wrapper library solution. But in small cases the reflection should be fine (and in case performance is not a problem for you).
If you need more info, ask in comments.