Lambertus is the owner and maker of the routable maps. His target is weekly updates, but it misses once and a while. So you could expect a new version this weekend or next.
And yes you can make your own version of the map for the Garmin. It requires quite some computer skills. The way to do it is here: http://wiki.openstreetmap.org/wiki/Mkgmap.
The forum section “Garmin Maps” has much of the discussion you might be interested in.