Cloud management tools are as varied as cloud uses. For this test, we chose five tools that each attack Cloud management from a different perspective.

There's "the cloud" and then there's Windows Azure.

Ubuntu 11.04 (nicknamed Natty Narwhal) marks a decided change in direction for the Linux-based operating system. The biggest change is that Canonical, the organizer of Ubuntu, is replacing the Gnome/KDE desktop environment with a new user interface called Unity.

The machines used included two Dell 1950s (one has 16GB RAM, other has 8GB, both have eight cpu cores), one HP DL585 G5 (32GB RAM, 16 cpu cores), one HP DL580 G5 (32GB RAM, 16 cpu cores), Dell Optiplex 740 (three-core AMD, 4GB RAM).

Nimbula's founders developed the Amazon EC2 public cloud system and are now working on Nimbula Director, which aims to partition internal cloud resources by authentication, along the lines of how EC2 works.

The potential benefits of public clouds are obvious to most IT execs, but so are the pitfalls -- outages, security concerns, compliance issues, and questions about performance, management, service-level agreements and billing. At this point, it's fair to say that most IT execs are wary of entrusting sensitive data or important applications to the public cloud.

On the surface, Apple's Snow Leopard Server feels like a $US499 maintenance release, but underneath, there's much more - improved performance, more polish and new apps focused on collaboration and content sharing.

Ubuntu Server is a fast, free, no-frills Linux distribution that fills a niche between utilitarian Debian and the GUI-driven and, some would argue, over-featured Novell SUSE and Red Hat Enterprise Linux.

Ubuntu Server is a fast, free, no-frills Linux distribution that fills a niche between utilitarian Debian and the GUI-driven and, some would argue, over-featured Novell SUSE and Red Hat Enterprise Linux.