In a global temperature update through 2012 [PDF], James Hansen and his colleagues at NASA's Goddard Institute for Space Studies report:
The 5-year running mean of global temperature has been flat for the past decade (emphasis added). It should be noted that the "standstill" temperature is at a much higher level than existed at any year in the prior decade except for the single year 1998, which had the strongest El Nino of the century. However, the standstill has led to a widespread assertion that "global warming has stopped".
But Hansen and colleagues argue that that the global temperature trend won't stay stopped:
... the continuing planetary energy imbalance and the rapid increase of CO2 emissions from fossil fuel use assure that global warming will continue on decadal time scales. Moreover, our interpretation of the larger role of unforced variability in temperature change of the past decade, suggests that global temperature will rise significantly in the next few years as the tropics moves inevitably into the next El Nino phase.
We shall see. If this plateau in global average temperatures continues for a few more years, it will call the projections made by current computer climate models seriously into question.