From Matt Cutts of Google, having to do with algorithms change: http://www.mattcutts.com/blog/algorithm-change-launched/

Another good one for understanding PageRank: http://www.mattcutts.com/blog/pagerank-sculpting/

This one has to do with site speed from Google. Matt Cutts says not to worry???:http://www.mattcutts.com/blog/site-speed/

Does anyone know how to reach Matt Cutts?