Like Thought on Wednesday announced the release of Opacity Express 1.0, a screen graphics editor for Leopard. It costs $39.
You can use Opacity Express to create paths, gradients, lines, text and other vector-based imagery; each layer can have its own opacity and mask. Filters are “live layers” that can be added to images and changed at any time.
A trial version is available for download.
Opacity Express requires Mac OS X 10.5 or later.