Yes!
I’ve used WordPress to create many large sites, that are by no means blogs. Sometimes the structure that WordPress uses, with the custom posts + taxonomies, etc., actually makes things much easier than many PHP frameworks.
There seems to be a big discussion in the PHP community as to whether WordPress should be used as a framework for general sites. It seems that Matt (the founder of WordPress) actually wants to keep WordPress as a blogging engine, however the fact that so many users are beginning to use WordPress for other means looks like this is inevitably going to change in time. The one thing that WordPress does lack is an effective caching mechanism, so you’re probably going to have to use a plugin for this (WP super cache is a good option). However, the fact that WordPress has so many functions created for you, makes it very much like a general PHP framework, even if many people argue against this.
From personal experience, WordPress can be a little heavy to create general-purpose sites that aren’t very big. However, it can be a dream if you take it on a case-by-case basis and you use your experience with WordPress to determine whether or not it will make your job easier.