In addition to what other people have already said, maybe it is worth pointing out a few things. Just by way of explanation, I have worked in bioinformatics for a few years now, specifically in genomics, so my take may be different to other peoples.

Finally, and this is specific to genomics I guess, and this is sort of a negative - the sheer scale of the datasets means that Perl is often not the best choice, either in terms of running time, or memory use ( I find this especially applies to BioPerl objects ). However, like Ruby, Perl objects can be very lightweight, if you don't mind writing your own. Ruby also has a growing BioRuby community, though it is not as large or well funded as the BioPerl community.

My second caveat is graphics and GUIs - users generally want to see and interact with their data, and I personally find Java the best option here, though Python is good too.

For a first language and for picking up the basics look no further than Perl, there have been discussions here and elsewhere before (Super Search and google will find them) about choice of a first language, so i won't go on... Then once your are more experienced and involved in bigger projects, you may well want to start thinking about Ruby or Java. But Perl is and will remain for some time, the industry standard.