I have a laptop (powerbook 15 g4) and it's a great computer, and despite it's age (2 years) it basically does everything I need it to. And 90% of what I'm doing is:
- editing text files
- reading rss
- reading pdf files
- command line things
The portability is really helpful, but, frankly, I often feel like I'm pulling around too much, and would like the computer that I lug around with me to not have to have everything on it, and I think that having a desktop to be able to manage the libraries database (pictures, video, music, pdfs, etc.) could make a lot of things easier. I mean truth be told, when I'm at home, all the computering happens at a desk, so having a desktop wouldn't hinder things.
If you were just going to have one computer, given what the author said, for a lot of people, particularly given how powerful a lot of laptops are, it makes sense to get a laptop.
I'd add to this, that there are lots of situations where desktops continue to make a lot of sense (other than production environments), particularly where a computer is going to be used by more than one person. That's something we don't tend to think about a lot these days, but I think it's totally an issue.