Yahoo! held a Yahoo Developer Day, aka Yahoo Hack Day, on September 29th, where a number of presentations were held on best practices for development and design.
I really enjoyed the presentation from Matt Sweeney, Senior Engineer on the Yahoo! User Interface Library team at Yahoo!, on “Web 2.0: Getting It Right the Second Time.” If you work on web sites, a video presentation of the talk has been made available on Yahoo! Video. I’ve embedded a copy here.