The intro, giving some historical background as to how our time system of months - weeks - days - hours etc. came to be, might have been a bit long for people looking for more technical stuff. I however found it extremely interesting as Joeri put in so many nice little facts about time (Why are there 24 hours in a day? Why 60 minutes in an hour? Why are dates before 1927 suspect? Why is Coordinated Universal Time abbreviated as UTC and not CUT?).
The technical part of the talk went on to be packed with useful information. How is time represented in computers? How do some common programming languages handle dates and time, and where are the gotchas? And then some really useful strategies to deal with the quirks, like how to store dates and timezones correctly and why you should always use a single source of time.
I learned quite a bit from this talk and I would recommend it to everyone having the chance to attend it, or at least go through the slides.