From Reddit, this should be in the OP
System features
Touch screen [T:0131]
SD card slot located on the bottom of the system [F:3]
Ethernet: example scenario given where dock has wired Internet connection; in console mode the system uses this connection, and in portable mode, the system can communicate wirelessly with the dock to access the wired connection [T:0560]
Sleep mode for both console and portable modes [T:0562]
"Share" button of some kind confirmed; referred to as a "record button" in the details for the left Joy-con; describes using it to take screenshots [T:0168]
Hardware/performance
Fan inside system, active in both portable mode and console mode [T:0419 + T:0556]
Dock does not appear to have a fan (thanks, /u/StinkBank) [F:32]
System uses CPU (and/or GPU) and fan at less than maximum in portable mode; in docked mode, it fully utilizes these. This enables outputting higher resolutions when docked [T:0556 - T:0558]
Ambient light sensor for controlling brightness [F:30]
System may be docked facing forwards or backwards (thanks, /u/MrMiyamoto) [T:0385]
Dock has 3 USB ports (thanks, /u/MrMiyamoto) [T:0464]
Controllers
Right Joy-con has IR and NFC capabilities; both have rumble and gyro [F:31]
Example: alternate Joy-cons with traditional dpads + sticks, or dpads + buttons [F:48 - F:49]
Small digital L/R buttons accessible on the "inside" of Joy-con (where it would attach to the system), for use when held like a sideways Wiimote [F:51] [T:0180 + T:0207]
Accessories
Example: head-mounted display accessory (simple VR headset) [F:60]
Joy-con Grip can charge attached Joy-cons (thanks, /u/Asuparagasu) [T:0672]
Various controller accessories given as examples, similar to Joy-con Grip [F:52 - F:53]
Gameplay
Multiplayer scenario example: 4 Joy-cons can be used on one system (does not specify a limit to the number of Joy-cons or Joy-con pairs usable at once) [F:37]
What the heck?
Vein authentication/vitality sensor: the IR sensor could be used to authenticate users by imaging their vein pattern; can also read their pulse [T:0495]
Missing/Unknown
Apparently no Ethernet port on the dock, but will almost certainly support USB adapter; see wired connection scenario above
Camera and microphone: not present
Analog triggers: unknown
Multi-touch/capacitive touch screen: unknown
Stylus: unknown; not sure if this would even be part of the patent?
"In other embodiments..."
The implications of passages like these are not clear. They are given as examples of things that may or may not change (differences or omissions) from the patent document to the final version, or future revisions.
4G/mobile: "Note that in other embodiments, the main unit 2 may have the function of implementing communication by connecting to a mobile communication network (in other words, a mobile telephone communication network), in addition to (or instead of) the function of implementing communication by connecting to a wireless LAN." [T:0400]
Camera: "Note that while the infrared image-capturing section 123 including an infrared camera is used in the present embodiment, a visible light camera (a camera using a visible light image sensor) or other image sensor may be used, instead of an infrared camera, as an image-capturing device, in other embodiments." [T:0451]
System itself could charge attached Joy-cons [T:0530]
System could output directly to a TV without the need for the dock [T:0542]
https://www.reddit.com/r/NintendoSwitch/comments/5ii58o/nintendo_switch_patent_megathread/