Other differences between the 1st and 2nd gen iPod touch:
- 1st gen has a black aluminum border around the screen
- 2nd gen has a full chrome border around the screen
- 1st gen only has a sleep/wake button and a home button
- 2nd gen has sleep/wake, home as well as volume buttons on the side
Go into settings and there should be an icon towards the bottom for Nike+iPod. If it isn't there, it's a 1st gen.