AP does the Mumbai (the Chennai, too)
AP, In a rather quick reversal after having said just over a year ago that it would stick with Bombay and not go with Mumbai, has now reversed course.
The official word:
Changes in AP style, reflecting names as used by the Indian government that have gained favor internationally and in everyday speech.So Bombay is now Mumbai and Madras is now Chennai.
I predicted this was likely after the Bombay/Mumbai train bombings.