Our marketing skills don't quite match those of Cupertino, so we called the feature by its technical name—"trickle sync"—but the idea is the same. Whenever you make changes to your calendars and/or contacts on your Mac, Spanning Sync v2.0 will immediately push those changes to Google (unless you have your sync interval set to "Manual").
Please note that Google doesn't currently provide the notifications necessary to enable "push" functionality from Google back to your Mac, so Spanning Sync will still poll for changes at the interval you set in the pref pane. We're lobbying Google to add notifications so we could add true two-way push to a future version of Spanning Sync. Stay tuned.