I've been reading TMC for months, looking at buyers guides, reading all sorts of posts and I've never seen this mentioned before. Not to say that others haven't noticed it, but maybe it isn't as well known to everyone. There is a pocket on the front of my driver's seat, right in-between my legs towards the floor. Fits my cell phone perfectly, and maybe some spare/emergency cash? I would NEVER think to look here.
It's the perfect spot for my gym parking pass that I have to hang from the rear view mirror. I like that pocket. Sunglasses go in the cubby under the center display.
This is where I keep my insurance and registration, as well as 25 flyers to put on top of cars ICING electric car charging spots.
To the OP...and new owners --- There is a thread here entitled something like "Things You Might Not Know About Your Model S". It has a great collection of such nuggets, although its success has lessened its usefulness - too hard to read through. If I recall correctly, mention of that pouch was one of the earlier posts.
At the Roseville SC I met a new owner who just took delivery that day. I asked him if he knew about the driver seat pocket? He did indeed and his wife said she liked the one on her side as well. Anyone else confirm seat pockets on the passenger side?
Originally only leather seats had the pouch and only on the driver's side. I guess that must have changed recently.