... But if you look at both sides of a Teensy 3.1, the entire space is pretty tightly packed with components, pads to access signals, marking to help identify the signals, and test points. I'm really not sure how practical it would be to add any sort of marking that's easily noticeable among the densely packed features and communicate clearly to anyone who's not already familiar with the product.
... Just sayin'. Of course, contrasting color is optional
And an actual logo would be better yet.
Further: The gist of a number of responses on this thread is that there are a variety of ways to determine whether a board is a Teensy, and which one it is, by noting certain chips, or arrangement of parts, plugging it in and probing its code etc. Yes, obviously, you _can_ forensically determine what you are looking at. I think comments like this have missed the point.
Presumably we don't think that it's a good idea for a supply chain to be flooded with components that have no Ids by which they can be immediately recognized? How would that be manageable at any scale, whether in a school, manufacturing environment, prototyping lab, etc? Do we expect to deal with resistors and ICs that are unmarked except for the packaging they came in? Of course not, it would be a nightmare. (Exception: SMD passives, and there you have to be super careful to get them from tape to board without mixup.)
Hey, we loves us our Teensies, but now that there are a few different models, and pushing into new niches, I for one would really appreciate them being labeled, so that, in the wild, I know what I'm looking at without an identikit, and someone on the phone can look at one and tell me what it is, and so I can issue instructions and expect people to follow them, and get not-specially-trained personnel to check an order or an assembly, and etc etc etc.
-- Graham