Actually, it's not another Wordpress but I think it's a good rival, with equivalent or better “usability/designabilty”. Where the roots of Wordpress are as a blog, C5 was designed to be a website CMS from the beginning. I'm pleased to announce that we're going to do a presentation on how to setup a site from start to finish and create a theme in 20 minutes or less plus an overview. Concrete5 is a CMS (Content Management System) that's a pretty mature and that's near and dear to my heart.
It's developed by a few guys up in Portland (Franz Maruna and Andrew Embler), has an active community and was closed source but opened up to be open source four years ago. http://www.concrete5.org/about/history/
I've made dozens of sites with it throughout the years and in my opinion it's one of the easiest CMS's to theme, maintain and use. Wordpress, Drupal and Joomla are certainly great, each in their own way, but Concrete5 is still my personal go-to CMS when I need something quick, that's easy to add content and theme, feature rich and highly intuitive.
It was one of the first of the main stream CMS's to have in-context editing and has the ability to “just move” sections of a page around at will plus pop in functionality like videos into areas with a click of a button, a built in sitemap tree that lets you create pages, move those around and manage permissions, a robust file and workflow manager, and an extensive and easy form creator.
Did I mention that they have a e-commerce plugin made by them so core CMS upgrades won't break your e-commerce site? You can literally get e-commerce installed in 10 minutes.
Like any CMS out there, all is not rosy in the garden and I'll go over some of its warts too. However, I feel it's one of the best CMS's available today. Their plug in ecosystem features a variety of free and paid plugins to encourage developers to keep up with updates or you can pretty easily roll your own. If you want to speed up your design and development process, have more stable websites and happier clients, I recommend looking into it. Here's a link to try out a hosted demo:
By the way, I'm in no way affiliated with Concrete5 nor are they giving me any money.
I just like it and want to share it with the SoCal Community!