That step was Argo.
Argo deployments began in 2000 and by November 2007 the array was 100% complete.
Houston, they have a problem. From the linked Vancouver Sun article:
So why are some scientists now beginning to question the buoys' findings? Because in five years the little blighters have failed to detect any global warming. They are not reinforcing the scientific orthodoxy of the day, namely that man is causing the planet to warm dangerously. They are not proving the predetermined conclusions of their human masters. Therefore they, and not their masters' hypotheses, must be wrong.
In fact, "there has been a very slight cooling," according to a U.S. National Public Radio (NPR) interview with Josh Willis at NASA's Jet Propulsion Laboratory, a scientist who keeps close watch on the Argo findings.
Willis insisted the temperature drop was "not anything really significant." And I trust he's right. But can anyone imagine NASA or the National Oceanic and Atmospheric Administration (NOAA) or the Intergovernmental Panel on Climate Change -- the UN's climate experts -- shrugging off even a "very slight" warming.