I was recently speaking at the 2009 PubCon in Las Vegas on both an Organic Site Review Clinic & an SEO Site Design Panel.
The Organic Site Clinic on Wednesday November 11th was only myself & Alan K’necht of K’nechtology where we were aligned on foundational & canonical SEO for the sites we reviewed as we are both sticklers for proper back-end coding.
We even came across a site that was using a MORE link to hide content at the bottom of each of their pages – the site will remain unnamed 
Later that Wednesday after lunch I was on an SEO Design & Organic Site Structure panel with Ted Ulle of Converseon, Lyndsay Walker of Canada’s Web Shop, Scott Polk of Search & Social Media.
Moderating this motley crew was Christine Churchill of KeyRelevance with QA moderator Taylor Pratt of nFusion.
We all agreed we would keep our presentations to under 5 minutes so people could ask plenty of questions and get some great takeaways rather than just simply hearing us talk on and on, on stage.
I spoke on foundational SEO concentrating on what I term the big 3 of the .htaccess, robots.txt, & Webmaster Tools – I included my presentation below:
Ted went over some great foundational design information while Lyndsay went into coding advice and Scott provided some great tips, but where I disagreed with Scott is on using file extensions over directories.
I like & respect Scott Polk as he is great speaker with a wealth of knowledge & experience coming from Bruce Clay thus I didn’t want to undermine him publicly so I simply nodded in agreement with Ted on stage with him stating he prefers directories.
All things being equal a page at abc.com/xyz.html has just a good chance to rank as abc.com/xyz/ but with the directory page you have the added benefit of not having to change reference links if you go to another web page format such as php, asp, cfm, etc plus I feel its better organizationally since you can place related pages & files in this directory giving them added keyword weight.
Scott stuck to his guns on extensions over directories while also being correct that you can simply resolve the new web page format issue in the .htaccess, but I still contend directories are better long term both organizationally & for SEO.
What do you think?