The fact that someone in Google wrote an application in lisp does not mean that lisp is now an approved language at Google. Wonder why the author came to such a conclusion.
Regardless, PG has a big smile on his face right now :).
Quite a few of the early comments are mentioning Clojure. Since it runs on the JVM, that might make more sense than CL for Google (whose main languages are Java and Python, IIRC).
Java, Python, and C++
I don't understand the conversation - I hope it isn't real, how can someone say "no" so immediatley - unless they are that uber smart, that they know the ins and outs of every language.
From the conversation buildup it looks like these requests (use Smalltalk, Lisp) were common at Google, thus could be responded to with "precomputed" no (i.e. it was not the first time VP had to ponder the request).