As far as I know, Google does not offer an official certification program for Android. However, I recently discovered a website called expertrating.com that deals in providing various kinds of certification. For example, this site provides a Google Android Programming Test that may be of some value to Android developers.
The Google Android Programming Test is described as offering 40 multiple choice questions, where each question has between two and eight options out of which one or more may be correct. Furthermore, the test is designed to take 40 minutes to complete.
Because it appears that the test does not include Android programming exercises, the only value I can think of for this certification is that it provides some assurance that the developer has a certain amount of theoretical knowledge.
I have yet to encounter any other kind of certification in Android.