At the PCC fall gathering last year Greg Johnson (PMEL/NOAA) spoke about his work examining XBT data and ARGO results, and the sources of uncertainties in calculating ocean heat content. This work is highlighted in a number of reports released in the last few days:
"Global change: The ocean is warming, isn't it?"
A News and Views article in nature.com by Kevin E. Trenberth
"Ocean Stored Significant Warming Over Last 16 Years"
a newstory on NOAA's website.