But it is! I really am lucky enough to get to do machine learning research at Google and code in Common Lisp!
See http://research.google.com/. Another way you can tell that this is an official Google project is the 'Google' label on the right-hand side of http://code.google.com/p/plop/, which is only added to code developed at Google that has been open-sourced.
Maybe one day if you're bored, you could tell the rest of us how you were able to swing a job at Google Research working with Lisp?
I don't know about these guys, but I've always been under the impression that if you're at Google, you're using one of their "Big 4" languages.... Heck, even Norvig is using Python! (I know, he was using it before he went there... but still).
I can't speak for the whole process, but a requirement is a PhD in an area Google cares about.
The research divisions of large companies are generally different than the production side. Researchers generally have the freedom to choose how to implement something.
I figure Google is too smart to restrict its hiring to knowing a certain set of languages, especially for its research division. Languages can be quickly learned, sheer badassery cannot.
a) Not everyone in Google Research has a PhD, though of course there is a bit of a correlation (also, plenty of "research" takes place in general engineering)
b) You do generally have to be very familiar with one of the Big 4 to get hired (C++ in my case)
c) Plop is kind of a weird edge case insofar as it is very long-term research, and really cries out to be implemented in a language where you have the same features at compile-time and run-time, and can conveniently represent and manipulate code as data (i.e. a Lisp). For doing plop in any other language, your first task would be to implement these features, which is rather a lot of work (believe me, I've tried ;->). For most anything else one of the Big 4 would be used, for the reasons Steve Yegge outlines...
Also, before anyone gets too excited, Google generally doesn't go beyond Java, C++ and Python. But we do have some special purpose languages internally, as well.
I think in one of Steve Yegge's epic narratives of life at Google, he said that only the "Big 4" languages can be deployed on Google's servers.
Does this mean, if you ever wanted your research to go "live" in a Google product, you would first have to rewrite in C++, Java, Python, or Javascript?
See http://research.google.com/. Another way you can tell that this is an official Google project is the 'Google' label on the right-hand side of http://code.google.com/p/plop/, which is only added to code developed at Google that has been open-sourced.
Cheers!