http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php - contains all the models used in the IPCC AR4.
http://tamino.wordpress.com/climate-data-links/ - contains a huge amount of climate data.
http://www.cgd.ucar.edu/ccr/ammann/millennium/CODES_MBH.html - An independend re-evaluation of a climate reconstruction.
http://www.ncdc.noaa.gov/paleo/pubs/mann2008/mann2008.html - Full data for a late 2008 reconstruction.
Data is available - maybe part of the problem is the complexity and quantity of the data.