[ALUG] How to use either wired or WiFi network, quickly/automatically?

I have an Acer Aspire laptop running lubuntu 12.10, when I'm at home I just plug in an ethernet cable but when I'm elsewhere I'm more likely to use WiFi. When there's no hard-wired connection the boot sequence wastes 2 minutes or so trying to get the connection up before continuing. What's the proper way to handle this (it's easy enough to remove the delay from /etc/init/falsafe.conf but that's a hack)? -- Chris Green