I have been doing some comparisons and calculations ever since the World Bank came out with this release. http://web.worldbank.org/WBSITE/EXTERNAL/NEWS/0,,contentMDK:23130032~pagePK:64257043~piPK:437376~theSitePK:4607,00.html
This division implies that the bottom 69% of India earns (at most) 28% of India's income and the top 31% earns (at least) 72% of India's income. This is an extremely simplistic piece-wise linear representation of the population-income Lorenz Curve, but it provides an implied lower bound of the Gini. The area under the curve (with coordinates of (0,0), (0.69, 0.28) and (1,1)) is 0.295, implying a Gini of ((0.5-0.295)/0.5) = 41%. To reiterate, this is just the lower bound. The World Bank Gini coefficient for India in 2010, however, is just 37.
If you separate the population into four distinct sets - at the world bank lines of $1/day (17% of India's population below this), $1.25/day (33% below this) and $2/day (69% below this), you get a lower bound on the Gini of 51!
If India's poverty stats are indeed correct, then we'd be almost as unequal as Brazil and much more unequal than China. But India's inequality stats belie that. Which of these numbers is incorrect? My hypothesis suggests the $2/day figure of 69% is over-stated, but there could be other reasons.
Incidentally, I've mailed the World Bank about this. Let's see if they get the time to reply.