I just don't see the point in ditching PHP now to learn ruby just because it has become the latest online fad, better to stick with what I know until I develop serious problems with PHP which I believe only changing languages could solve.
Don't learn Rails to make a career out of it (although that may end up happening!), learn Rails to expand your mental models.
And don't just learn Rails!
Learn Django. Learn Sinata. Learn Erlang-Web or Nitrogen. Learn Smalltalk. Learn TeX. Learn JavaScript (actual JavaScript). Learn Node.js. Learn Meteor.
Learning a language doesn't mean "ditching" anything. You're adding!
And one more thing: Ruby[sic] is far from the latest online fad. That would be JavaScript and Node. Rails was the latest online fad back in 2007.