I just published new Distro versions for Asterisk 1.8 and 10 based on Centos 5.8 and the latest 2.6.18-308.4.1 kernel for Centso 5.x. I know we were a few versions behind on the latest kernel and wanted to get that updated for everyone and get DAHDI and Wanpipe compiled for this kernel.
You can use the upgrade scripts from here http://www.freepbx.org/forum/freepbx-distro/distro-discussion-help/stable-release-versions for stable versions and
here for Beta versions http://www.freepbx.org/forum/freepbx-distro/distro-discussion-help/beta-release-versions-for-asterisk-10-distro.
You will now see the latest download ISO on the download page end in .58 not .57. Those are the versions that are built on Centos 5.8.