I want to spend some time learning a general-purpose interpreted language. 
I know a little Perl, but not a lot, and just a little Ruby.  I've also 
used Octave/MATLAB and R/S fairly extensively, but those languages are 
more special-purpose than general-purpose.

I haven't really used other similar languages.  Now I want to learn one 
and get good at it.  What is the best choice?  I want my choice to be 
future-oriented. I can see why Perl is a good choice because of all the 
Perl code out there (especially in bioinformatics), but I'm wondering if I 
should learn Ruby instead of Perl.  Not sure -- how do the futures of Perl 
and Ruby look to you guys?  Or is there an even better choice than either 
of those two?

I will want to use the language to manipulate data files, but I also want 
to be able to do more with web application frameworks and 
model-view-controller systems.  So Ruby on Rails would be a possible 
direction, but I'm not sure if knowing Ruby actually helps with 
understanding Ruby on Rails.

All opinions are welcome!

Mike