A close runner up in the service bus category is FUSE ESB, offered by Iona (makers of Artix ESB) after its acquisition of LogicBlaze. FUSE ESB is still being merged with Celtix, a previous open source ESB endeavor that Iona undertook with ObjectWeb. When all is said and done, FUSE ESB will include Apache-based foundations for message brokering, service bus, SOA framework, and routing.
The Sun Open ESB 2 – still in beta – is also promising, thanks to enhancements in development and administration tools for its Java Business Integration (JBI) runtime and GlassFish app server. And don't count out JBoss ESB, WSO2 ESB, or OpenAdaptor. This is one field that will only become more fertile with time.
We end with our pick of the Bossie for server virtualization. Several open source products split the votes here, but Xen won out over the competition. After all, it’s the virtualization project that sparked several commercial ventures aimed at unseating virtualization king VMware, and it's part of several mainstream Linux distributions. Xen is a solid baseline hypervisor for Linux, and it adds features seemingly every day. OpenVZ, a stellar example of OS-level virtualization, was the close runner-up. Like Xen, it supports only Linux guests; the difference is that OpenVZ requires all guests, or "virtual private servers," to share the same OS kernel.