Since 2010 March, there were some issues with the dumps of Wikipedias. Due to this, statistical data for the past 2 months was not available. Hence, I was not able to compile the statistical information of Indian Language Wikipedias for the month of 2010 April. The issues are fixed now and the report is finally published today (2010 June 28) in the site http://stats.wikimedia.org by Erik Zachte.
The logic I used to categorize Indian language Wikipedias in this report is mentioned in this blog post. The PDF of the report (for 2010 May) is available here.