From: http://management.silicon.com/government/0,39024677,39150672,00.htm
A UK man has been fined £500 and sentenced to 12 months' conditional discharge for hijacking a wireless broadband connection.

On Wednesday, a jury at Isleworth court in London found Gregory Straszkiewicz, 24, guilty of dishonestly obtaining an electronic communications service and possessing equipment for fraudulent use of a communications service.

Straszkiewicz was prosecuted under sections 125 and 126 of the Communications Act 2003.

Police sources said Straszkiewicz was caught standing outside a building in a residential area holding a wireless-enabled laptop. The Crown Prosecution Service confirmed that Straszkiewicz was 'piggybacking' the wireless network that householders were using. He was reported to have attempted this several times before police arrested him.

The case is believed to be the first of its kind in the UK.

Last year, 21-year-old Brian Salcedo was sentenced to nine years in a US prison for siphoning credit card numbers over a wireless network from hardware store Lowes.

Most certainly easier to install or security by default would help out.  You're right, that most computer users don't know what an IP address, or mac address is.