* Adoption - Rails is being heavily adopted, especially with the startup community, but also state agencies, hospitals etc.
* Community - Rails has a strong community of core devs, plugins devs, conferences, books etc.
* Jobs - Tons of Jobs in my experience. We have a hard time finding good Rails/Ruby devs. I have checked the market, seems like there are plenty of Rails jobs across the country. Check out: http://jobs.37signals.com/
* Scalability - Yes, Rails can scale. Check out: http://rails100.pbworks.com/Alexa+Rankings Ever heard of Hulu, JustinTV or Big Cartell?
* Fun - Ruby was designed for programmer happiness