In a story about Linux Distributions as web servers, CentOS is listed in the top 8, with about 1.5% share of the Linux webservers on the internet. This equates to nearly 100,000 web server machines 
From the article:
Quote:
The most successful newcomer is CentOS, which repackages the same software as commercial rivals, while offering free community-based support.
Full article ...... oh, and Debian is doing OK too

We are absolutely thrilled with the popularity of CentOS in the last 6 months and look forward to continued growth in the future.