When invoking the application organization mode in iPhone OS 3.0, you can now shift through multiple pages in a direction simply by holding the app to one the other sides of the display.
Previously, in iPhone OS 2.0, you had to move the app to the edge to invoke a page shift, then move it slightly away and back again to shift another page. This typically caused applications on each page you shifted past to get rearranged, which was especially irritating if you have a lot of full pages.
In iPhone OS 3.0, you can simply hold the app to either side of the device display to keep switching past pages; no organizationally destructive back-and-forth teetering required.