There are now posted to CentOS Extras for CentOS 4 and CentOS 5 new packages for NX (nx-3.3.0-14) and FreeNX (freenx-0.7.3-2).
NX is an enterprise-class solution for secure remote access, desktop virtualization, and hosted desktop deployment built around the self-designed and self-developed NX suite of components. Please see the NoMachine web site for more information about the NX libraries.
FreeNX is a GPL implementation of the NX Server and NX Client Components. See the FreeNX website for more information.
The NX packages in CentOS Extras are built from the OSS sources from NoMachine and provide the NX libraries, and the FreeNX packages provide the required server software to use the NX libraries.
CentOS also provides an NX client called QtNX (qtnx-0.9.0-3), but only for CentOS 5.
See the CentOS Wiki for information on using NX and FreeNX on CentOS.