Wordpress, as they say themselves is
" ... a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. Wordpress is both free and priceless at the same time."
It's a great system that allows people keep a blog on their site, in fact you can build a CMS site around the blog.
Wordpress can also be configured to allow video and audio content, so the client can easily share video through their YouTube onto their site.
The best thing about it is the ease of use, clients of ours that we've setup with Wordpress have always found it easy to get to grips with, even some with serious cases of technophobia!