CentOS 3.5 is now the default version of CentOS 3.x for all architectures.
Once all mirrors have synced users running yum update will automatically be updated to version 3.5.
This is equivalent to Redhat Enterprise Linux Version 3 Update 5 with some extra updates rolled in. The number of extra updates depend on the architecture, with x86_64 being the latest produced and thus most up to date.
The single CD server iso is still at release 3.4 and work is being undertaken to produce the 3.5 version in the next several days.
Thanks go to Tru Hynh and Pasi Pirhonen for their work in producing this release.
Lance