I'm not saying that actual smugness doesn't exist, but almost all the time it's actually just projection from someone who's used to being in the know now struggling to understand something new.
Remember when you explained to someone using a language lower on the power spectrum (VB or PHP maybe) why they should use all the cool stuff that you can do in Ruby or Python, how much more productive they would be, how much more fun it was to work in? You thought you were helping them and showing your excitement, you wish someone had told you this a long time ago!
Unless you are a world class educator they were confused by some parts, threatened that their investment in their current language was losing value and worried they might not be able to function in this new world and therefore protected their ego by seeing you as smug.