There are lots of shortcuts to making turkey gravy, but there's really no excuse for any of them ;-) Gravy does take some time. So does brining your bird. Both are infinitely worth it!
Make turkey stock
This can be done the day before the big event, when you prep your bird for brining. Remove the neck and giblets, add them to a large saucepan along with a carrot, a celery stalk, and 1/2 an onion. Also add about a dozen black peppercorns and a bundle of rosemary, thyme, and a bay leaf. Add about 2 quarts of water and bring it to a boil; reduce and simmer for at least an hour. Strain out the solids and make sure you have about a quart of liquid.
What about the giblets?
Well, we happen to like 'em coarsely chopped, but some people gag on them. It's your choice whether to chop and add them back to the stock or not. One of our friends (Bill from the Grill Team) puts his through a food processor because he likes the taste but not the texture.
Make a flour slurry
Another thing you can do ahead of time if you want. Add a scant 1/2 c of flour to 1 c of cooled stock in a lidded jar. Shake until very well-combined. You'll have to reshake it just before adding to the gravy.
Deal with the drippings
Once the bird is done, remove it to a platter to firm up and pour all the drippings into a fat separator. It usually takes from 5 to 10 minutes for the fat and other juices to separate, so in the meantime...
Deglaze the pan
Add either 1/2 c of water or white wine to the pan and bring it to a low boil across a couple of burners. Scrape up all the lovely brown things with a wooden spoon.
Some assembly required
Add about 2 c of stock and the separated juices to the pan, leaving most of the fat behind. Bring it to a boil and whisk in the slurry. Cook, whisking steadily until it thickens. Add as much additional stock as you need to make the gravy the consistency you like.