Stick a Strat middle pickup in a Tele and you have a Nashville Tele. This wiring was made popular by Nashville session players in the 1990s. A typical configuration would be to install a Duncan Hot Stack in the middle, and to wire its top coil to a dedicated volume control that was tucked in between the Teles's normal controls. Brent Mason's Tele has a similar configuration. The idea behind all of this, of course, was to add tonal flexibility by adding some Strat coolness to a Tele's coolness.
Fender ties the three pickups to a 5-way switch - rather than the standard 3-way - and does not use a third knob. While this reduces the tonal flexibility somewhat, it cleans up the guitar by getting rid of the third knob, which is a tight fit on a Tele's control plate. This produces most of the commonly-asked-for tonal options, and is the most popular 3-pickup Tele wiring.
Position 5: Neck Pickup
Position 4: Neck + Middle Pickups (Parallel)
Position 3: Bridge + Neck Pickups (Parallel)
Position 2: Bridge + Middle Pickups (Parallel)
Position 1: Bridge Pickup
(1) Capacitor, .022µF Orange Drop
(1) Jack, Switchcraft, 1/4" Mono, Long Bushing
(2) Pot, CTS 250K Audio, Low Torque (.250" Bushing Length)
(1) Screw for Shielding Ground Lug
(1) Shielding Ground Lug
(1) Switch, Oak-Grigsby, 5-Way, Single Wafer 2-Pole
(1) Treble Bleed Kit for Single-Coils
(2') Wire, 22 AWG Cotton Push Back w/ Tinned Overcoat, Black
(2') Wire, 22 AWG Cotton Push Back w/ Tinned Overcoat, White
(2') Wire, 22 AWG Stranded Silver-Plated Copper, Black PTFE
(2') Wire, 22 AWG Stranded Silver-Plated Copper, White PTFE
(1) Professional, Fully-Illustrated Wiring Diagram