Sacha Grief on not wireframing:
I start straight in Photoshop. I work fairly quickly, so I know I can produce a decent first draft in a couple days.
And that first high-definition mockup will be much more useful than a black-and-white wireframe to make design decisions.
Basically, the only way to really judge a design is to use a live prototype. The further away you get from that the less accurate your insights will be.
So for me, Photoshop mockups are a nice middle-ground between accuracy and speed of execution, while wireframes aren’t that much faster to produce while being vastly less representative of the final product.
I completely agree with Sacha. A few weeks ago, we started the process of planning a iPhone app and instead of wireframing the app, I quickly mocked up a design. Immediately my ideas came to life and was much easier to demonstrate and explain to others as it was much more familiar to them than a wireframe would ever be.