From the official BitWeaver website
bitweaver is an application framework for content management. It is a fully functional web application and CMS, and is used to power every page on this site. It is truly open source, community driven, object oriented, and written in PHP. We use Smarty Templates and ADOdb to support many databases including Postgres, Firebird, Oracle, and MySQL. 
Bitweaver 2 is well structured and powerful!
All modules (forum, wiki, blog and more) installs automatic if U like. No mumbo jumbo with mis-matched plugins. Several changeable themes. More then 20 switchable Gala standard column formats in just 1 click. All modules free open source in compliance w. std CSS and XHTML. Ajax inside. Installs in plain english on most (all?) php-servers. Absolutely a top choice for extended blogs and small to big portals w. community approach. Downside: Not very fast. Full installation ~15MB. I'm just an impressed noob (no profit).
Bitweaver is an open source content management system. Its speed and power are ideal for large-scale community websites and corporate applications, but it is simple enough for non-technical small site users to set up and administrate. It comes fully featured on install but is easy to extend.
Out of the box Bitweaver comes with a full set of features you want in a CMS, such as: Articles, Wiki Pages, Blogs, Categories, Image Galleries, Calendar, Message Boards, Email Marketing Newsletter, User Management, Choice of Database, Languages, Theming, Comments and so on.
Bitweaver Features
This is the list of features you get when you download and install Bitweaver. Features come bundled in what we call Packages. There is a core set of Packages which all other Packages require, naturally we call these Required Packages. The rest are all optional, and you can turn them on or off depending on the features you would like on your site. Add On Packages
There are additional Packages which for one reason or another are not included with the current release. These can be downloaded seperately and installed in Bitweaver. Visit the Add On Features page to see what is available.
Download:http://www.bitweaver.org/wiki/welcome+to+bitweaver.org
Demo:http://www.bitweaver.org/wiki/