No, I haven't gone over to the dark side. I just happened to start using two operating systems on my machine—GNU/Linux and GNU Emacs. Now that I've switched to Gnus for mailing, I basically spend all my time in Emacs and the browser. Sure, I've got the occasional xterm up when I don't feel like using eshell (mostly for ssh), but in general it suffices.
Anyway, I still don't feel like I've grokked Gnus very well yet, so I still keep Evolution open. But even if I don't end up liking Gnus a ton, I'd rather have a great editor and a poor mailer than a great mailer and a terrible editor. Gnus is kind of... different.
The other awesomeness I've recently discovered is Conkeror:
It's an extension for Firefox that recognizes that using the keyboard for everything is a much more efficient way to do things. I quote, "You should never have to reach for your mouse. To make sure Conkeror remains pure, I do not own a mouse." That's something I can really admire! I'm still on the fence about switching from Epiphany, but it's really intriguing. What I'd really like is gecko-mode for Emacs, but I understand that the rendering engine is pretty primitive.
Oh yeah, and here's a photo of my desktop's heatsink. Compressed air is your friend.