Apparently you aren't allowed to release applications on a Mac without a trendy brushed metal motif somewhere on your application. I read a while ago on someones blog about how to create this effect but haven't been able to find the blog entry again. That means I was forced to implement it myself. Although the code is mine I take no credit for the technique behind it.
Fill an Image with random monocrome values.
Optional, apply a black->white->black gradient blend over the image to give the appearance of a shine.
Finally apply a blur across the image to give the brushed look.