Quoting from the rPath official announcement:
rPath, provider of the first platform for creating and maintaining software appliances, announced today the ability to create virtual appliances that run on the Xen 3.0.3 hypervisor using rPath’s rBuilder.
The rBuilder platform allows software developers to combine software applications with Linux and related open source components to create virtual appliances that can be instantly provisioned and run on the Xen hypervisor and XenSource’s XenEnterprise virtualization platform.
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Reflecting the strong community demand for appliances on the Xen hypervisor, rPath has made many of the most popular projects on rBuilder Online available for download as virtual appliances for Xen 3.0.3. Examples include LAMP, MediaWiki, Gallery Photo Server, Port25 Mail Server, Music Player, OpenFiler, Cacti Network Graphing, MySQL, and PostgreSQL…