These are quite common here in Los Angeles county. They are very much like the Spanish Padron Peppers, with similar flavor, similarly erratic heat, and wrinkled appearance, but are a lot longer and narrower.

Here is the dominant way in which both Padron and Shishitos are used. The photo is with Padrons, but I usually do it with Shishitos, because Padrons are nearly impossible to find around here. The effect is nearly identical.

Padron Peppers

I'm a bit more careful today than I was in 2011, I hope.