CirculatorMap.com is up!
That means you cannot only conveniently see the different Circulator routes, but there is a live map telling you where each Circulator is.
This is especially convenient for Penn Quarter residents who are in the middle of a lot of Circulator routes. You can also assess whether you should go to the 9th and F stop, for example, or whether it will be faster to hop down to 9th and Pennsylvania.
Here is a map of part of the route from the Convention Center to the Southwest Waterfront. The arrows are actual buses and their direction of travel (you can see them move on the screen on the website):
There is also a list of each stop on each route and the time until the next Circulator gets to that stop.