Apparently, I'm not the only one - the BBC reports that "what is scampi?" was one of the most popular Google searches of 2011. And in response, the Fish Society posted a video explaining what scampi is - the tail portion of a type of lobster, not a prawn like most people assume. (Prawns are crusteaceans that look like large shrimp.) Okay, so now I'm more confused than before - are we making a dish using both shrimp and lobster or is there something else entirely? Scampi and Chips, which bills itself the "No. 1 Scampi related site in the world," answers that question by pointing out that Americans are wrong to call the dish "shrimp scampi." (That site also points out that the French are wrong about everything. Trying to figure out what French scampi was just led to more confusion, mainly involving translations, so I gave up.) Food Timeline provides quotes (some as early as 1964) that tried to explain what shrimp scampi was.
When looking up the definition of "scampi," the result is, "1. Large shrimp or praws, esp. when prepared or cooked 2. A dish of shrimp or prawns, typically sauteed in garlic and butter and often topped with bread crumbs." But how can it be shrimp if it's actually lobster? Ugh, I have other things that need my attention.
At this point, I think it's best to just acknowledge the fact that the definition has changed and "scampi" can also refer to a cooking method. This seems to be supported by the fact that there is Oyster Mushroom Scampi and Chicken Scampi.
So, back to shrimp scampi. Judging from these recipes from the Food Network, All Recipes, and Simply Recipes, shrimp scampi is shrimp cooked in butter, garlic, olive oil and white wine. Seasonings vary by recipe. Seems easy enough - I'd probably make it, if I was more of a shrimp fan.