From The Washington Post:
To request bike routes, select “Bicycling” from the pull-down menu below Google Maps’ directions form. As a company blog post explains, the site prioritizes off-street trails (designated with thick, dark-green lines) over separate bike lanes (thinner, light-green lines) over designated bike routes (dashed, light-green lines) and also tries to avoid hills, busier streets and crowded intersections.
This has been in the works for some time, I blogged about it back in July, 2008. Looks like it’s live now. It’s not perfect, you may end up being routed a longer route than you could find on your own, but if you’re new to cycling it might be a good way to start. You can always explore alternatives on your own when you have time.
They do have a way to suggest corrections, hopefully people in the know will add to the database. I haven’t tried it out yet in my area since I’m already pretty familiar with the roads around here and know where I am willing to ride and where I’m not. Perhaps it’s targeted more towards people who are unaware of established bike routes or trails in their area.
If you’ve given this a try let me know how you liked it.