In 2006 Nike and Apple showed that new combinations of existing technique can result in useful and lucrative products when they launched the Nike+iPod sportskit. Basically it is an iPod connected to a pair of jogging shoes and it gives the user information like distance travelled and calories burned via the earphones and the display.
This intersection has now turned into an arena of competition as Samsung and Adidas present the result of their cooperation - the miCoach. It is more or less the same concept but the device used is a mobile phone instead of a music player. It includes a heart-rate monitor, a shoe sensor and a Webworkout journal that keeps track of workouts.
Read more about technical details and a comparison between the products in this Washington Post article.