I've been brining for years. The authority on this subject is Cooks Illustrated magazine - Google their website for all the details of the process. The magazine is great if you are really into cooking.

Important points about brining, some of which have already been made in this thread:

-Too long or too strong makes for a very salty bird. Check the website for the correct strengths and times (they have numbers for short strong brines, and longer weaker ones to accomodate your timing needs). Don't remember them off the top off my head, but I'll look it up and post them if anyone's interested.
-Keep it covered and cold; blue-ice packs work well if you don't have adequate refrigeration. You can buy a proper-sized plastic tub with a good cover at WalMart for about 2 bucks. I wouldn't use any metal other than stainless steel due to the corrosive properties of salt water and the possibility of leaching undesirable metals such as aluminum into your solution. This is a good time to be scrupulously clean!
-Even with proper strength and timing, the pan drippings are usually too salty to use. You can roast some (cheap!) turkey legs the weekend before and make a dandy turkey stock out of that for gravy.
-Brining works by denaturing the cell walls, preventing them from rupturing and hence losing water, during the cooking process. A brined bird weighs something like 10-15% more than an equivalent unbrined bird due to better retention of water.
-A brined bird is diffucult to brown, often coming out with a splotchy gray-brown color. Basting with melted butter helps somewhat with browning, but as stated before does little else for the bird. The best way to achieve good browning is to brine the day before, and set the bird uncovered on a rack in the fridge overnight to dry out the skin. This makes a big difference, and a nicely browned bird results.
-The benefit of adding other flavors to the brining solution is minimal - with the exception of sugar, they really impart little to the bird. The herb and butter rub (especially under the skin), and aromatic veggies such as onion and celery with herbs in the cavity will be by far the dominant method of getting flavor into the bird.
-Some sugar in the brining solution for a chicken works well; the sugar taste is noticeably out of place in a turkey if you're going for the classic taste most folks expect.
-Ideal cooking temps are 160F for the breast, and 175-180 for the dark meat. Salmonella is killed after a few minutes at 160, but much over that will just result in a dry breast. Brining gives you a little more leeway - I've accidently taken a breast up to 170 without undo drying, but 160 will give you an incredibly juicy breast. You will not appreciate dark meat at 160-165 however, it should be higher. The way to achieve these disparate temperatures is to start the bird breast side down to concentrate heat on the thighs and legs, then flipping the bird halfway through cooking to brown the breast side. This method is also detailed by Cooks Illustrated. I haven't dropped a bird yet - don't be shy. Also, a shallow roasting pan works better than a deep one, allowing hot dry oven air to circulate around the bird better. With too deep a pan, steaming instead of roasting becomes more predominant.
-Stuffing the bird usually requires extended cooking times that will overcook the breast meat. If you really still want to do it, you can preheat the stuffing in the microwave before stuffing the bird so it is up to proper temp at the same time the rest of the bird is. I cook my stuffing separate, using the stock I previously made from turkey legs.
-Let the bird rest at least 20 min after removing from the oven. This allows the reabsorption of juices into the meat. Don't worry, it'll stay plenty hot, in fact the temperature will contimue to rise after you've taken it from the oven for a good 10 minutes. If you carve it without the resting, the juice just spills out all over your cutting board. This is important for nearly any cut of meat.

If you've read this far, you may be interested enough to try it. You won't regret it, it's really worth the little extra effort!

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2002 E320 4-Matic
2008 Subaru Outback
2009 Subaru Forester