alexx:
So obviously Google see that value of adding it.
Given the huge number of different languages in India, that should not suprise anyone. However it is by far the most widely spoken language and considered the primary official language (together with English) of India. On a global basis, Hindi, when counted with Urdu, is one of the top 4 in terms of the number of native speakers (several hundred million). That's a lot of potential phone sales.
It is one thing for Apple and Android phone makers to come to a country and sell to the english language market, but another thing for Nokia to support those languages and then take away that support.
Take a look at the share chart for the last six months, and note the relationship between the announcment of Nokia adopting Windows Phone and the drop in share price in mid February 2011. Selling for 8 EURO earlier this year, quickly dropping to 6 EURO and now almost down to 4 EURO.
http://uk.finance.yahoo.com/echarts?s=NOA3.DE#symbol=noa3.de;range=6m
IDC seems to be the only one that is saying that and clearly the investors don't think much of that advice or they would be buying Nokia shares, not selling. Given that you appear to be such a strong supporter of Nokia going to Windows Phone, you must consider the current share price to be a bargain. Have you purchased any Nokia shares?
There have been several suggestions about what the upcoming disruptive device might be. It appears something will be shown at Nokia Connection 2011 in Singapore on the 21st June - suggestions are.
1. Nokia Windows Phone... seems too soon to showing be a pre-production unit of a future phone and displaying a mock-up of a device that will never be sold won't help their credibility.
2. Meego device - it needs to be something special to be truly "disruptive", but it appears that one Meego device has been through FCC type approval and has been almost ready for some time, so this is what I'd expect to see. The counter argument is that if Elop doesn't believe in Meego as the future of Nokia, what is he doing in Singapore announcing the N9... or perhaps another manager will present this one.
3. There have even been rumours of a 1GHz clocked S40 device which seems crazy, but if Symbian is going to be phased out and Windows Phone is positioned at the high end, something is going to need to cover the middle ground. Can S40 move upmarket? This could be quite "disruptive" but a 1GHz S40 device still makes no sense.
Good on Google for adding Hindi as an additional language. Still not a deal breaker in India. Smartphone has apps and you install apps on them from the marketplace. How many apps do you know that are in Hindi? Rural uneducated people in India need hindi on their cheap Nokia phones and it's already there. India does not have an official language defined in the constitution. The fact that when you see Indians speaking and understanding English much more comfortable than Chinese or Koreans tells that English is widely spoken there in School and Work. It took Google a lot of major updates before Hindi was added. I am sure if need be MS will add it in a later update.
As for the chart, it's not going down due to the WP7 announcement, it went down becuase of the financial data released during investors calls. If it was WP7, then I can understand Feb announcement going down, but why did it go down again in June when Nokia recently again did an investors calls. The graph below proves Nokia's shares going down since 2008 and if you notice the yellow highlighted mark, Feb downfall is nothing compared to previous years.

IDC is not the only one making the prediction reagrding WP7 overtaking iOS by 2015, Gartner too is as well.
http://www.enterprisemobiletoday.com/features/article.php/3930311/Gartner-Predicts-WP7-Will-be-No-2-in-2015.htm