My wife got me How to Grill two Christmas's ago. Since then, it has provided many nights of pleasant reading. Steve and his books have taught me many things. One of the things I learned, that has turned into a family favorite, is smoked Turkey. I smoke my turkey on a Kenmore Elite 3-burner gas grill. This has it's pluses and minuses. If you like a heavy smoked flavor, a gas grill is not the way to go. However, if you prefer just a slight smoke flavor the gas grill is perfect.
I take a mixture of Oak and Cherry chips, soak them then make about 7 or 8 foil smoking packs. I make sure that the chips are in a thin layer in the foil packet (If you lump them too much it will take too long to start smoking.). I then will put the first pack in the grill on one side. As soon as it starts smoking good I put a second pack on the other side. Once the first pack is charred through I replace it, alternating sides throughout the grilling. This provides a constant supply of smoke throughout the cooking process.
As for the turkey, I probably over prepare, but it has great results. I start brining the turkey the night before. Then just before smoking, I inject the turkey with a solution of olive oil, beef broth, lemon pepper seasoning, kosher salt, and bbq rub. I know the beef broth sounds strange, but it really works. I then rub the skin with olive oil, kosher salt, and cracked black pepper.
When the turkey is cooked to 170 degrees internal, I take it off the grill and let it sit for at least 20 minutes. This results in a wonderfully moist turkey with breast meat that literally melts in your mouth.
I am looking seriously at getting a barrel smoker and trying my hand at real smoking. I look forward to trying the turkey out on that.