CentOS 4.1 ia64 is now available on the mirrors. CentOS 4.1 is just a re-spun ISO containing all updates through June, 10th 2005, (include all those released in EL4 Update 1). If you already have CentOS 4.0, downloading the new ISOs is not required to upgrade to CentOS 4.1.
The ISOs can be downloaded via Bittorrent from this directory:
http://mirror.centos.org/centos/4.1/isos/ia64/
(or your closest mirror)
You can upgrade CentOS 4.0 to 4.1 manually now by changing the file /etc/yum.repos.d/CentOS-Base.repo file and replacing $releasever with 4.1 on all the repos and running "yum upgrade".
If you don't want to manually edit anything now, in about 1 week CentOS-4.1 ia64 will automatically be made the default version and you will be upgraded when you run yum any time after that.
Here are the CentOS-4.1 release notes detailing differences between CentOS-4.1 and the publically available upstream sources: http://mirror.centos.org/centos/4.1/os/ia64/RELEASE-NOTES-en.html
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The below Release Notes are provided {and copyrighted} by Red Hat®,Inc. The CentOS Project redistributes these original works (in their unmodified form) as a reference for CentOS-4.1. CentOS-4.1 is built from publicly available, open source SRPMs. The CentOS Project is not in any way affiliated with the provider of the open source SRPMS.
http://mirror.centos.org/centos/4/docs/html/release-notes/as-itanium/RELEASE...
------------------------------------------------------- Another announcement will be made when CentOS-4.1 becomes the default version for all updates.