Perhaps this is an old post but I had to ask the answer.
I had a big problem to find the right answer to this question.
Although the function of the led lights has its advantages, these functions can also be very annoying sometimes.
On Motorola Motolux, in my case, I was constantly blinking blue led.
I think that is not a sign that I have an incoming or missed calls.
I tried to find what it is and here's one answer that for me had success.
I think this blinking comes from third party applications.
I turned off all notifications from gmail,gtalk Facebook, Twitter, Yahoo, etc. .. all of the notification of third party applications.
Finally, another application for SMS HandcentSMS, appSettings-DefaultMessagingapp-ALL (SMS&ММS) and suprise
working, no flashing blue led....