GM or not, the development goes on anyway...
Every new release of Safari is a good thing, but the GM designation is essentially meanginless to me--no more than a minor item of interest. (The resulting appearance of Safari as the default on new Macs would be a nice step, though.)
Before GM:
Safari is stable, full-featured, and free. But will still periodically get further enhancements, features and fixes.
After GM:
Safari is stable, full-featured, and free. But will still periodically get further enhancements, features and fixes.
Conclusion: it hardly matters what does or doesn't change for the GM. Development will go on, and Apple will keep listening to feedback. GM doesn't mean the product is "final" because software NEVER needs to cease evolving.