JeanS, Steven McIntyre and other online "auditors" have had their way with the recent Shaun A. Marcott et al. Reconstruction of Regional and Global Temperatures for the past 11,300 Years.
The procedure that Marcott used appears to have lost more information than it gained in combining a variety of 73 paleo temperature reconstructions from around the globe. Using the same procedure used for combining modern era instrumental data, the paleo reconstructions could have been more optimally interpolated to establish a procedure for combining various types of paleo reconstructions with different sampling frequencies, variation and record length.
With most of the same "skeptics" involved that led to greater confidence in the accuracy and limitations of the instrumental surface station record, "crowd sourcing" a paleo-climate absolute and anomaly temperature record regionally and globally should be a worthy project for the climate science junkies.
Food for thought.