The old air-cooled Volkswagens had aluminum engine blocks and heads, not magnesium, but they burned so quickly if you had a gas leak that you'd think they were made of combustible metal! ("voice of experience" here).

Go into an automotive aftermarket wheel shop and you'll see plenty of wheels made of magnesium alloys. Light, strong, and expensive! And I believe Ferrari uses magnesium wheels on their cars.

I saw a pair of magnesium ATB platform pedals on one of the bike parts websites, was thinking of buying a pair for my MTB. Not worried about 'hot footin' it, but wondering about the durability of magnesium if its used as part of a bearing set-up since its somewhat brittle.