Question: At work we write a small to moderate amount of scripts to aid us in normal development. We have some people that are more comfortable in python, some in perl, some in php, etc...

Sometimes I think it is best to let people work in a language they are most comfortable with. This can mean that sometimes people can do a better job on a script (as they know more tricks in one language). It can also lead to less development time per script.

Other times I think that we would benefit the most from standardizing so that there might be more shared libraries and so that we don't get into the situation of "I can't work on that script because I don't know python".

Do you think that we should standardize or let people choose for each script they write?

Answer: 
I would be inclined to let people choose, *and* hire people who are comfortable at learning new things. Gaining basic fluency with almost any language should be easy enough for a good developer. And for small scripts where the original author isn't far away, it's even easier.

The second part of the above is the hard part, of course. But you'll end up with a more flexible, more knowledgeable team.
I would advocate standardizing on a couple languages. "Thou shalt use either Python, or Perl, or Ruby. Not Rexx, nor PHP, nor NewBatch, nor aught other, for thy brethren ought to be able to read thine writing without undue despair or cutting of their skins".