The ECB is playing a dangerous game and Krugman has spotted it. The bank is only providing life support at the last minute. The euphoric reaction in the eurozone markets to what was announced at the recent EU summit was a major over-reaction. One false move by the ECB (by, say, coming in with bailout money an hour too late) could crackup the entire system. This would not be a bad thing from my perspective---though Krugman would likely view it as the end of the world.
The ECB game, though, is in line with the thinking of the banksters and Germany: keep the pressure on the F' PIIGS in an attempt to force them into a more unified banking and fiscal zone. That means keeping rescue attempts at the edge, only when it appears a country is going over the edge.