It’s been a long time coming, and it still looks very much a beta, but at last those of us who use Safari have our own version of Google Gears.
If this post is a clue, then hopefully sometime soon:
"Improvements to Gears can be used by developers immediately. Gears is available today on Firefox (for Windows, OS X, and Linux), IE, and IE Mobile. Implementations for more browsers and platforms are in progress."