I am interested in statistics on number of users getting post ban, for different SX sites. Is such information available? Is it possible to get such information from the Data Explorer? (Then it would be enough to show me how, I can make the SQL request myself.)
While we don't have public statistics for the number of users who have been question-banned, we do have access to the number of clicks the "we are no longer accepting questions from your account, see here" link has received. As pointed out by Arjan, you can use the http://goo.gl/C1Kwu+ link to access stats about how many times that shortened link has been used. It sounds like you do need to be logged in to Google services to see those stats, though.
As of today (Feb 9, 2013), that link has been clicked 36000 times. 12200 of those clicks came from India, 5870 from the U.S., and 1865 from the U.K, with the rest of the world well behind those countries. I believe the same link is used for all Stack Exchange sites, so you can't separate out where the bans were taking place, but I imagine Stack Overflow accounts for the vast majority of those clicks.