None at all for me

 

in 2.1 the trackball only comes on when the light sensor detects low light. hold your finger over the right 'notification light' (light sensor) and move the trackball around. it should come on. it's a great idea if you think about it.

 

Actually, just gonna be a naggy Nancy here, you hold your finger over the other little block that's on the other side of the ear piece. The notification light doesn't detect light, it gives it off.

 

you're funny.

one serves as a notification light...the other is a sensor. and if you hold your finger over it and move the trackball it comes on. or in darker lit locations... if this doesn't happen for you, well sprint's 2.1 update is a joke - so if you have that...yikes.