As a dev-channel user myself, this is all stuff I've seen for months. Google has three versions of Chrome, each of which are called channel releases. There is the dev, beta and stable channels with the dev being the most rapid release and the stable being, well the more stable tested release.
The dev version of Chrome is actually a whole version ahead of the stable channel now and is currently at its 4.x release. There are at least two key items in Chrome 4 that are not yet in the new Chrome 3 stable release.
First off is the Google Extensions system. Chrome 3 stable doesn't have it, but I don't doubt that this will be the last version of Chrome stable to ship that doesn't have extensions.
The new stable release also does not include the bookmarking syncing capability that is currently in the dev-channel release. Those are both really interesting features that will bring the functionality of Chrome to the next level.
Those features aside, for everyday users the stable Chrome 3 release will be a leap forward in terms of speed. Google states that the Chrome 3 release is 25 percent faster than the most recent stable release.