Matlab replacement

Thank you folks, I didn't expect any comments on my first entry about ocaml and scientists. 

I am also looking for matlab replacement,  although matlab is `de-facto' standard for signal processing.

As far as I know there are several (free) alternatives:

octave

R

Python (scipy+numpy), some people in our university was productive using this language as a glue to fortran routines. Although I tried to use it several times I never progressed far enough. I got frustrated, when python interpreter didn't like my tabs for code alignment. 

And there is even Ruby for scientists.

My first computer language was perl, so I might try it for signal processing.

I would like to hear about the succesful transitions from matlab to anything else. Especially in the areas of signal/image processing, communications.