Here’s a pretty interesting list of layout engines. I stumbled upon this list when I was researching if Dreamweaver Studio 8 was using Gecko or Trident, the engines for Firefox and IE respectively. I found out that it doesn’t; DW8 apparently seems to be using Opera’s engine, Presto.
This is very important, in my opinion. In Dreamweaver, it has a preview/WYSIWYG feature that emulates the browser and that means you are viewing your webpage in Opera, which is roughly around 1% of the browser market.