FWIW, you can do some pretty sophisticated 'mining' of information using MarkMail.org... the main CentOS list is archived there, as is this devel list. I know the lists are archived several places (such as Gmane) but MarkMail is pretty good for drilling down when searching - not so good for just browsing. I first came across it when looking for some information related to the R-project. Here are a couple examples:
A search for 'dnsmasq' on the main CentOS list:
http://markmail.org/search/?q=dnsmasq+list%3Aorg.centos.centos
And a listing of all the CentOS mailing lists.
http://markmail.org/search/?q=+list%3Aorg.centos
They provide the code for a small form to embed in an existing site so users can enter their search string, hit 'Go', and it takes them to the MarkMail page where they can waller around in all the mailing list goodness they want ;)
As far as integration into the forums... it looks like there is a 'mail2forum' project... but it is current only for phpBB2, not phpBB3. Eventually (as with most open-source projects) it should get caught up... at that point it looks like it should be possible to bridge the gap between the lists and the forums. Until then, I don't think neglecting the forums in favor of the mailing lists (or vice versa) would be prudent.
HTH,
Monte