- 37 Signals use them! They even made a cheezy video about it!!
- Build quality is good and its a fashionable tech accessory
- Single platform across a team of developers makes for an easier life and Mac is the obvious choice
- Textmate, the modern standard Rails text editor in many ways, is Mac only software
Ruby on Rails is not, last time I checked anyway, a Mac specific programming language / web framework.
Having just moved to the latest Ubuntu (12.04 LTS) as a platform for my RoR projects i’m finding it a comparably slick alternative to the OS X monopoly.