A Google search turns up lots of dead ends. Some are pretty good, but most are completely useless. I tried a couple of the configuration variations suggested in the article and its comments and didn't have much luck. It turns out that it's actually easy. Just follow these simple steps:
- Download Gnome Gmail
- Install it! I used the .deb because I run Ubuntu.
- Go to System -> Preferences -> Preferred Applications
- Select Gmail in the Mail Reader drop down