A few months back, I wrote a little snippet about rolling your own CMS. Although still my preferred method of tackling the IT Industry wide CMS problem, you sometimes need a solution up & running with the quickness. So if rolling your own is not an option and you need something profession, cheap and in a demonstrate-able state ASAP, consider Alfresco.
Although it's billed as an Open Source Enterprise Content Management System, it does have Web Content Management Capabilities through a Web Content Management Module. (This may sound like an afterthought, but it's not; it's actually quite robust and is built on a very powerful enterprise scale infrastructure).
Alfresco is an open source J2EE application built on Spring, Hibernate, Lucene, JSF, and all your other Java best of breeds technologies. Best of all, it's founded & built by some of the people behind Documentum and Interwoven (among others). They've brought together their lessons learned and best practices in both the Web & Enterprise Content Management spaces and built Alfresco in an open source manner. It's really a beautiful thing. Their business model is the RedHat model - provide a kick ass product and make your money off support.
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