Wasn't ITA Software using CCL before their acquisition by Google? I wonder why they switched to SBCL. Right now CCL seems to be rather understaffed but this wasn't the case when they switched, as far as I know.
Back in 2009, before the acquisition, a developer ITA software presented at the SBCL workshop (audio here: http://www.sbcl.org/sbcl10/materials/cracauer-talk.ogg), talking about the company's use of SBCL. They'd also talked about using CCL; the last I heard was that they used one on desktops, the other in prod deployments.
CCL was primarily used for another project, and the decision to do so was dramatic and made many people unhappy. This thread has some juicy details from the time: https://news.ycombinator.com/item?id=911163