I'm surprised they make it a paid service "The Reuters Market Light will now introduce a small customer charge of INR 60 per month." If this could be a profitable business, it will be yet another example of "there is money to be made at the base of the pyramid".
The article doesn't provide enough details on how they exactly do it. Here is another article:
http://www.businesswireindia.com/PressRelease.asp?b2mid=13897

"Reuters Market Light has its origins in a project-idea conceived by a Reuters employee whilst on a year's Fellowship at Stanford University. The employee was being sponsored by The Reuters Foundation on Stanford University's Digital Vision Program. From this initial idea, the project was taken on by Reuters development team, implemented and this year successfully trialled in India. Reuters Market Light is an example of Reuters commitment to empowering the world's financial markets through blue-ski thinking, technological innovation and fast and responsive implementation."