When my D&D DM decided to take a break from the big chair, I stepped in to introduce the group to Shadowrun. I started by handing out things like the "History for the Reality Impaired" section of the core book, "Anatomy of a Shadowrun", and other such things, to set the tone, months before the current campaign came to a stopping point. I gave them movies to use as inspiration, such as Blade Runner, Ghost in the Shell, and Johnny Mnemonic. This prepped the field, and allowed them to get a feel for the setting. I gave them a nice long talk about how in Shadowrun, you're not heroes. You might be good guys, or bad guys, or somewhere in between, but you're people who do jobs for money.
And then I gave them pre-gen characters, and explained the character's 'role' to each of them, and ran them through the Food Fight starter as a combat tutorial, moving on from there. After this run is over, I'll let them transfer the Karma and nuyen over to new characters, or let them redesign characters if they wish. The group isn't normally a fan of pregens, but this made them acceptable, as a learning device.