If you use Hardy in a regular laptop fashion, i.e., having it automatically connect to available networks, wired or wireless, it works great. Just set roaming mode on both of your adapters and network-manager will take care of the rest. My problem was wanting to have it act a little differently. I want the wired connection to have a static IP, and having the wireless connected to another network at the same time by DHCP. Here's what I found out to be the simplest way:
1. edit /etc/network/interfaces to have this in there:
iface eth0 inet static
2. uncheck "roaming mode" from the wired connection in Administration > Network, and set the static IP info.
Editing interfaces is necessary; otherwise the system for some reason doesn't know how to take care of eth0, which will be dropped by network-manager after taking off "roaming mode" and set static. Keeping "roaming mode" with wireless connection gives you the option to easily pick an available wireless network from the network-manager applet.