I would stick with PHP and try codeigniter. Going down the 'Rails' or 'Django' path. Ultimately just gives you a new toy. I wouldn't say it was worth it. But that depends on what your goals are.

Ruby is a nice language though. I do all my non-web stuff in that.

I highly recommend Peter Cooper's Book: Beginning Ruby, Link:http://www.amazon.com/Beginning-Ruby-Novice-Professional/dp/..., if you'd like to get started with it.