Is there a conflict when a laptop has an active Ethernet cable connected and available wireless 802.11b/g connection? If so, which technology would take over?
Hilarious. No network connectivity 'takes over' based purely on the connection type!
This is simply a question of the ip routing table ('netstat -rn') and which order you get connected and if an ip address is assigned, etc.
For example, if you are on working wireless network and then plug in a wired cable to an active network and get a DHCP address, without disconnecting from the wireless network, you will actually be connected to both networks. The default gateway (the 0.0.0.0/0 route in the routing table) will have a lower metric for the connection that happened second, or the wired connection, which means all traffic not destined for your local (directly connected) wireless or wired network subnet will be sent to the wired network's default gateway.
I use this to my advantage during my consulting work by utilizing cellular or guest wireless network for my default route so my VPN client (etc) works, while being able to print locally, etc. This is not the most secure way of doing things, but it works and I hope answers your question...