The new observatories currently being built, upgraded or designed represent a big step up in terms of complexity (laser
guide star, adaptive optics, 30/40m class telescopes) with respect to the previous generation of ground-based telescopes.
Moreover, the high cost of observing time imposes challenging requirements on system reliability and observing
efficiency as well as challenging constraints in implementing major upgrades to operational observatories. Many of the
basic issues are common to most of the new projects, while each project also brings an additional set of very specific
challenges, imposed by the unique characteristics and scientific objectives of each telescope. Finding ways to share the
solution and the risk for these common problems would allow the teams in the different projects to concentrate more
resources on the specific challenges, while at the same time realizing more reliable and cost efficient systems. In this
paper we analyze the many dimensions that might be involved in sharing and re-using observatory software (e.g.
components, design, infrastructure frameworks, applications, toolkits, etc.). We also examine observatory experiences
and technology trends. This work is the continuation of an effort started in the middle of 2007 to analyze the trends in
software for the control systems of large astronomy projects.