Siemens is supposedly working on a mobile phone with a gas sensor built-in.
This sensor could be used for dedecting the alcohol concentration in the users blood via breath analytics. The sensors could also be used to detect ozon concentration in the air or if the user has bad breath. Siemens has a mobile phone prototype in the lab with the alcohol tester working. The alcohol test mobile phone is about 2 years away, if it ever hits the market.
More details in the german Technology Review.