The Keynote Address by Marcel Molina, Jr., titled What makes code beautiful includes a very insightful discussion of code style and how code can be too clever. In light of the popularity of DSLs and Metaprogramming in the Ruby community, this talk is a helpful reminder to think twice before using advanced Ruby features.
Ezra Zygmuntowicz (InfoQ conducted an interview with Ezra recently), talks about Exploring Merb. Jared Richardson talks about using Using C to Tune Your Ruby (or Rails) Application.
Ken Auer tells the history of Smalltalk and how it and it's problems with adoption in the industry relate to Ruby in the talk Does Ruby Have a Chasm to Cross.
Hidden gems can be found in the Lightning Talks video, filled with short talks which cover topics such test/spec (Behavior Driven Development without RSpec), JRuby as scripting language for Java game programming, a quick discussion of the Methodphitamine idiom, Ruby rules engines, WPF GUI apps with IronRuby, creating static websites with Rails, and many more topics.
These videos and more can be viewed in the browser, but can also be downloaded as AVI files at the Confreaks website.