Nate Shedroff: User-centered Design is an approach (with many variations) to creating experiences (whether products, interfaces, events, or other media) for people with their needs in mind. Usability is one of the primary focii but only one of several. Others include usefulness, desirability, legibility, learnability, etc. The benefits are that these experiences are often easier to use and learn; more appropriate in terms of functions and use, and more compatible with existing processes.

Good overview article on UCD process. Also, some info on benefits and shortcomings of heuristic reviews.

Link:
http://www.digital-web.com/interviews/interview_2002-10.shtml