Andy Rutledge wrote an article that points to the pitfalls and benefits of wireframes. Pick the tools for the job. I strongly believe that you must understand your client and understand their goals before you do anything. As a designer you create for others and not for yourself.
Wireframes can be useful in situations where communication is poor. When you don’t have a chance to sit down with the client face to face. When they want one thing and their boss wants something else. Getting design patterns and content structure approved can be a critical to a project. Reducing the noise in such situations becomes a challenge. If you’re on a project that’s swamped with use cases, wireframes and functional design with a fully documented interface description then I wish you luck, strength and wisdom. It can be great for a new design and terrible when you doing a redesign.
37 signals in known for their slightly quirky approach, no wireframes, no Photoshop and go from idea to HTML. It may sound a bit strange but in many cases this approach is very effective.
When you boil it down wireframes is a dialogue between you and the client about what they want from their site without commenting to much on the aesthetics of the project. However, sometime aesthetics is all you need.