The Russians have probably been looking VERY closely at their plans for next year's Winter Olympics in Sochi, all along - the security machine there is going to be massive and pervasive. The last thing they want is some terrorists mounting an attack there. Chechnya is just a few hundred miles away and there's been this string of major terrorist attacks in Russia itself by Chechyen groups a couple years ago - the school occupation at Beslan, residential houses blown up in Moscow and so on. With hundreds of dead.
The number is almost certainly in the thousands; there were around 700 deaths from the apartment bombings and Beslan alone, let alone the slightly less high profile subways bombs, bombs on planes, bombings of government buildings and the like. And that's without looking into the somewhat grey area where organised crime and terrorism interweave.
It's also worth noting that a significant number of the foiled terrorists plots over the past few years have featured terrorists from Chechnya, Dagestan and other Soviet republics.
The Russian situation will be interesting, partly because there will be legitimate groups looking to use the occasion to hold protests as well. Russia will have to balance giving them reasonable freedom (albeit such freedom is always restricted during events such as this) and the security situation.