Jumpzero has released Gradient 1.0 for Mac OS X (10.6 or higher). It’s available for US$4.99 in the Mac App Store.
It’s a tool for web designers. Gradient streamlines the creation of CSS3 gradients by taking care of writing the vendor prefixes needed to build a gradient that’s compatible with modern browsers.
You only need to pick the colors you’re after from your mockups (or fill the fields in the input pane) and tweak the gradient properties, selecting linear or radial type and deciding the direction or the center position. The rest is taken care of by the application. What’s left is copying the resulting code and pasting it in your text editor of choice.