This is possible, because "Blacklist" System in Russia is still testing. The "Black List" update 2 times a day (09 a.m. and 09 p.m. Moscow Time), and all Russian internet providers must check this "Black List" and block sites. But in reality, some providers do it manually. But i think government fix this problem soon.
This is not a system against only gambling sites. This is a system for total censorship in internet. Now this system works in test mode. Russian goverment try to create somthing like "Golden Sheeld" in Mainland China. If you don't know what is this, please spend several minutes and read this:
http://en.wikipedia.org/wiki/Golden_Shield_Project
Russian Goverment at this moment want to create the more strongest system. There are rumors, that they want to create within next several years "Russian Entranet". This is really dangerous.