For those who do not have heated seats and would like them, there is a manufacturer who is an OEM supplier to Ford (among others, including Mercedes and Porsche) for the same: Heated Seat Kits (
http://www.heatedseatkits.com/index.html ).
These seats, like all aftermarket seat heaters, are relatively easy to install and come in a number of sizes/styles/optional controls and cost from $90 and up for a single seat.
In additional, the company ALSO makes a "massager" seat kit (with an option to add a seat heater with it), something that it describes as follows:
- Individual Remote Control included
- Optional Seat Heater
- Complete kit, with template for ease of installation
- Four different massage settings (low, low back, upper back, lower & upper back)
- 6 or 8 massage motor option
- Detailed instructions with detailed diagrams
- All new wiring harness with latest connectors
- Power: Standard 12 volts
- Can be installed in any vehicle
- Used by Upholsterors and Manufacturers worldwide
- 1 year Manufacturer Limited Warranty
- Anti Drowsy Deterrent System
- On special now for $95.00 each (6 massage motors) or $110.00 each (8 massage motors)
- Limited time offer while supplies last.
Although there may be other OEM suppliers to the major auto makers, this company is the only one I have found in my brief search. They offer detailed instructions for installation of their products and, perhaps somewhat suprisingly, appear to be one of the least expensive manufacturers of such kits (do a web search and you'll see: $128 was the least I found elsewhere).
FYI: aftermarket heated seat and massager seat kits available 
