The relationship between the number of slides and the length of a PowerPresentation presentation is changing. Seth Godin claimed to have gone through 154 slides in 54 minutes "without a sweat". At a rate of 1 slide every 3 minutes, we could change Guy Kawasaki's 10/20/30 rule (10 slides, 20 minutes, font 30 or bigger) into 60/20/30. The "10" refers to the number of ideas you can handle in a presentation, not the number of slides. Obviously slides need to look completely different for a presentation like this, nothing like the bullet point loaded "overhead projector transparencies" we still see in too many presentations today. UPDATE: Today I stumbled on this interesting blog posting by Andrew Abela that clearly separates 2 types of presentations: ballroom-style (big audiences, beautiful graphics, few words, high page turnover, the 60 i.s.o 10) and conference room-style (the classical consulting project final report full of dense facts and figures).