A lot of trucks use Twitter, Facebook, apps, and networks. In the SF Bay Area, you will find trucks banding together in networks.

The licensing of food trucks in many areas is stricter than restaurants for health code checks which IMO makes them safer for those worrying (in my area trucks get twice annual inspections, brick and mortar only get once).

I have been hitting up food trucks since high school (am 30 now) and have found that most have regular haunts and will post a weekly schedule that stays relatively the same from week to week.

Denver actually has quite a few food trucks. I have spoken to food bloggers who frequent them. I would encourage those interested in specific regions to also seek out food blogs that specialize in food trucks. I know of a few in most metro areas in the US.