It looks like things have gotten worse on the e-mail clients front in regards to CSS compatibility.
I was hoping that things would be getting better and e-mail would become more like web page design and conform to standards. From what I’m reading things are moving farther away from it. Tables are almost a necessity for layout and the only style tags that are used by most readers are the inline ones. These are the least preferred kind.
David Greiner has updated his year old post and talks about how far we have gone back. If you are e-mail marketing you should read this.