The only one that would be plug and play would be the one that Toyota sells. I don't know if it is plug and play or not, but it's the only one that comes to mind that would be.
Remote Starter at Sparks Toyota-Scion, Myrtle Beach, SC
After reading the instructions from the Sparks website, it appears it is plug and play, but it looks like a pretty good job to get it in. Also be aware that people have reported that the range on the OEM unit is only about 80 to 100 feet or whatever the range is on your stock key fob.