The classification error at ArXiv spontaneously corrected. I can confidently recommend that anyone interested in Unification and Quantum Gravity (in the normal everyday number of spatial dimensions) listen to today's seminar talk by Garrett Lisi, at the ILQGS hosted by Jorge Pullin. Pretty much anyone here at Beyond forum will IMHO get something out of it. There are two versions of the PDF slides. Be sure to download the larger (version 2) and have them ready when you start the audio. In the audio GL periodically says which slide he is discussing. Here is the direct link to the PDF (this is to the second improved PDF with the extra slides.) http://relativity.phys.lsu.edu/ilqgs/lisi111307_2.pdf Here is the direct link to the audio. http://relativity.phys.lsu.edu/ilqgs/lisi111307.wav Besides the moderator the main people you hear commenting and asking Garrett questions are Abhay Ashtekar and Lee Smolin.