Starbucks has rocked the boat in the kosher world.
As Starbucks has added to their food menus, their cleaning practices (as far as cleaning cooking utensils) has come into question with respect to the separation of utensils that are used for coffee-brewing purposes and utensils used for (non-kosher) food purposes. Knowing that all utensils are (or may be) washed together in hot water, it now becomes difficult to say that a brewed drink at Starbucks is 100% kosher since it has been cleaned and washed together with utensils used in the production of non-kosher food.
In light of all of this, the Houston Kashrut Association (HKA) put out a statement aligning its policy with the Chicago Rabbinical Council which you can read here; essentially, the new guidelines are that the full-service stores are to be avoided (for the most part), and that the kiosks (like those in Target and Randalls) are ok. Please read more details in the CRC policy which easily outlines the dos and don'ts so that you know what you can order.