There are several ways of getting help in CentOS as summarized on the Wiki Help page. The most commonly used CentOS-provided venues are the mailing lists and the forums. However, when people encounter problems or simply want to find out some information, they most likely just go to google.
I performed some searches on google for commonly used terms with the “site:centos.org” added and then counted the number of hits that pointed to the mailing lists (M/L) and did the same for the forums. The result is summarized below. Assuming most people will not go through many pages, I collected the results from the first 50 links (that’s 5 pages with the default of 10 per page).
Search term M/L Forums
============ === ======
install 0 21
installation 0 4
kernel 10 11
driver(s) 3 24
DNS 11 29
postfix 19 20
sendmail 22 16
selinux 5 10
apache 0 23
httpd 6 30
xen 38 7
kickstart 20 12
crash 16 11
panic 10 19
While I do not claim this is a representative result, I do notice that the forum posts tend to be found more often than the M/L posts. One notable exception (among this small set of searches) was “xen” — most of them were from the centos-virt mailing list (what else do you expect? 
).
Also, I am not trying to compare the significance/importance of the two help channels, either. I only want to emphasize the fact that, in the age of google everything, many users come to read those posts and, therefore, we need to maintain the contents of the posts as accurate as we can.
I’ve heard about a plan to merge postings from both channels into a single database. That would become a valuable souce for all CentOS users.
Good Evening,
Such a process is also not only about using a single data source.
There are several attempts of merging forums and mailinglists (e.g. nabble offers a forum ML frontend).
I am not sure if something like that is already available for common forum solutions (like phpBB).
Best Regards
Marcus