Eucalyptus currently has a Release Candidate 1.6.2-rc1 for hardy beta testers.
The current stable release of Eucalyptus, version 1.6.1, can be installed from source or as binary distribution-specific packages (CentOS, Ubuntu, Debian, and openSUSE). Note that, as of 1.6.1, the debian packages (for Ubuntu and Debian users) are being made available via a Eucalyptus debian package repository (click the links below for more information on setting up your system to use the repository). You might want to skim the Administrator's Guide to understand the steps involved for each method. Here are the files necessary for each of the methods:
32-bit
64-bit
32-bit
64-bit