An article I worked on has recently been published on MSDN. The article, Understanding Field Controls and Web Parts in SharePoint Server 2007 Publishing Sites, documents the differences between using field controls and Web Parts in Office SharePoint Server 2007 Publishing Sites. It contains a lot of explanation on the underpinnings of each technology and implications of picking one over the other. In addition, I spent a good bit of time talking about the Content Editor Web Part.
Here's the article summary on MSDN:
SharePoint Server 2007 Publishing sites empower content owners to manage content on a site without involving the IT staff in the day to day management of a site. Content owners can use one of two tools provided by developers, field controls and/or Web Parts, to manage content on a page. This article covers the details of field controls and Web Parts, the differences between the two and offers best practices on when one should be used over the other.
I'd consider this required reading for anyone doing Publishing sites. Why? It is a major point of contention and one I see many organizations get themselves into rough spots on. I've written a few times about this issue on my blog here, here and here as well as a guest post on the ECM team blog. I'll also be talking about it at the SharePoint Best Practices Conference in London in April. It's also one I hear Microsoft gets a lot of support calls on. Make sure you know the difference before embarking on your next Publishing site project!