Is there a site show cloudstack source code contribution by companies like openstack community heartbeat http://www.stackalytics.com/
Sebastien Goasguen's Update on Apache CloudStack Community Analysis will give you a sense of the contributions.
However, you won't see a lot of companies: AFAIK, Apache accepts contributions from individuals and not corporations.
This isn't a programming question, so I have posted the question on the CloudStack developers mailing list
Update: Feedback from Apache CloudStack developer mailinglist