As of August 6th, Debian squeeze has been frozen with Eucalyptus on board! Eucalyptus 1.6.2 has been available in Debian's sid archive since May 2010. sid is Debian's unstable archive, where packages are available prior to being promoted to Debian's testing archive. The current testing archive, named squeeze, is destined to become the next official stable release of Debian (version 6.0). Now frozen, no new features can be added to the contents of the squeeze archive, and the focus is now on polishing, bug fixes, and documentation. We at Eucalyptus are pleased to be part of the next stable Debian release.
Read more at http://www.debian.org/News/2010/20100806