That's pretty neat. Personally, I find GoogleEarth and the ability to look at satellite images combined with elevation data more useful than the GoogleMaps database of bike routes, since not all of the less obvious bike routes around here are in the database (yet). However, you can help add bike routes to GMaps by using Mapmaker.

Here's a good example of a fun connector I found using GoogleEarth, you'd never know the little trail in the middle of the screen was there unless you lived nearby and happened to walk around in the park to the east, because the western end of this little connector is totally hidden from the road (Mark Dabling Blvd.) by the railroad tracks (odd rectangles in the picture are a train of empty coal cars). Just for fun, note that the headquarters building for the USA Cycling organization is right behind this trail: