You can become certified in Google Analytics by taking the Google Analytics Individual Qualification exam. The test costs $50.
You can prepare for the exam by studying at Google's Conversion University. Studying the material here will help you squeeze more out of Google Analytics -- even if you have no interest in certification.
If you're interested in preparing for the exam more quickly, a good resource is SEO Rabbit's Google Analytics Individual Qualification Test Notes. This is sort of the "Cliff Notes" version of the Google test prep material.