The followings are only my personal opinions.
Joomla!, a very popular CMS (Content Management System). Easy to use, a lot of extensions, free to download. Yet, not all the extensions are free. Some are commercial extensions. Some commercial extensions allow you to download for limited days of trial. Easy to install, easy to use. A lot of people like it.
On the other hand, CakePHP, not a CMS but only a web application framework (I mentioned CakePHP in this post because this is the only web application framework I used, I haven’t tried about CodeIgniter or Ohloh). Comparing CakePHP with Joomla isn’t quite appropriate because they are not same category. But for me, both of them are PHP and used to develop websites.
When looking for the Joomla extensions, most of the great extensions are commercial. Just like when I am search Windows software, a lot of software are commercial. However, CakePHP allows me to write my own applications. It is more developer friendly, freedom of programming. It is easy for me to write application using CakePHP rather than using Joomla API framework to write applications. Just like using GCC to compile the source code is easier than using Microsoft Visual C++ to compile the source code.
Therefore, in the sense of content management, Joomla is more appropriate than CakePHP. Though using CakePHP can produce something like Croogo, CakePHP itself is only a web application framework. However, using CakePHP can also produce CMS.