According to the good folks at Wikipedia, Pop Tarts started out as an idea that the Post company had for a side to accompany breakfast cereal, and as a way to showcase a method of preserving food in a foil pouch, which had originally been designed for dog food. They apparently screwed up the timing of the release of the product, though, which gave Kellogg the opportunity to develop their own version six months later in 1964. The Kellogg version was so popular that they could not keep up with demand.
The original version was no frosted, due to a concern that a frosting could not withstand the heat of the toaster. Three years later, someone figured out that frosting could, in fact, hold up in the toaster, and a frosted version was released. The first Pop Tarts came in four flavors: strawberry, blueberry, brown sugar cinnamon, and apple currant. It seems that apple currant fell out of favor, probably because no one knows what currants are anymore. Today, as we know, there are a variety of flavors, some of which seem slightly ridiculous.
Unlike some of the lawsuits that plagued our previous project, the only noteworthy legal drama that Pop Tarts had to deal with was a claim that the pastry caught fire in the toaster. Apparently, a university professor later performed an experiment proving that the Pop Tart could, in fact, produce a flame of up to one foot if left in the toaster too long. Consequently, Pop Tarts now have a warning on the packaging reminding you not to leave them unattended in your toaster.
There are also complaints from heath groups with criticize the product of falsely claiming any kind of health benefit because some of them are filled with "fruit". In times following this, the company has removed, and then added again from the packaging that Pop Tarts are made with real fruit. Personally, I'm not sure why anyone would be particularly offended to find out that a baked good, which is meant to be stored for a long period of time without refrigeration, is not actually good for you, but that's just me.
But I get the appeal. It's like a baked pastry any time of day or night. You can eat them without heating them up, you can carry them with you. They're just as good as a dessert or a snack as they are for breakfast. I don't think for a second that my homemade version will be as convenient, but it's worth trying them out, anyway.