The following are recommended (but not under our supervision) at any Starbucks: Americano [with paper cup, without “shot” glass], bottled Starbucks drinks with “KD”, Expresso [with paper cup, without “shot” glass], and tea with hechsher [paper cup]. Rav Heinemann of the Star-K researched Starbucks. Keystone-K disseminates information based upon our own research and that of the national kashrus agencies. It is not the position of the Keystone-K to usurp the position of your rabbi and poseik. The results of the research and the reasoning behind it may be viewed at:
http://www.star-k.org/articles/kosher-lists/1709/starbucks/
http://www.star-k.org/articles/kashrus-kurrents/kashurs-kurrents-2011/summer-kashrus-kurrents-2011/601/dont-drink-the-coffee/
Some people make the mistake of assuming that everything in an establishment is kosher if they see observant people in the establishment. Starbucks is a clear example of the error of this assumption. While some items are acceptable, others are not.