Multiple connections and metrics?

[Joe Barnett <thejoe gmail com>]

A co-worker was showing me the neat way that windows XP deals with
mutiple connections.  Instead of bringing connections up and down as
cables get plugged in/waps get too far away/etc, all interfaces are
brought up whenever they can be connected.  So, for example, a laptop
with wireless, ethernet, and a bluetooth/gprs connection will have 3
interfaces up.  The routing table is set up such that all 3 routes
exist, but have different metrics.  So (hyptothetically) the ethernet
will have a metric of 0, the wlan 20, and the bluetooth 60.  When a
packet is routed, it chooses the route with the lowest metric.  This
means that instead of losing connection, and then having to wait for a
new connection, the network connection just gets re-routed to the next
lowest metric connection without a break in connectivity (or at least
with a noticably shorter break).

2 questions:

1) can routes  in linux be set up this way? (I've only seen metrics of
0 when i run the route command, man route says the metric is not used
by recent kernels...)

2) would it make sense for NM to try to do things this way?

Thanks,
-Joe