Hi jhickman,
I am very sorry for your loss. This must be very difficult for you and the pup left behind. Dogs do grieve the loss of a friend whether it be human or another animal and the best thing you can do is keep the remaining pup as busy as possible. Introduce new toys and games, do the things that he loves to do with you. Also keep in mind that dogs do pick up on their owners energy and if you are thinking about your dear old friend, your dog is able to pick up on this mood. Everyone needs to go through the grieving process and each go through it in a different way and amount of time. I am sure that once you start feeling a bit better your pup will to.
Here is more on grief in dogs. http://www.petplace.com/dogs/grief-in-dogs/page1.aspx
There is a beautiful story of the Rainbow Bridge which may help to comfort you. Read it when you are ready. Take one day at a time and know that there is no right or wrong way to the grieving process. It is as individual as you and I. It may help you to write out your memories of your pet, the good, the mischievous, and the bad times.
Pet Loss (the rainbow bridge)
http://www.petloss.com/
dog training consultant
24 years training & behavior,pet first aide, Therapy dog eval., PA Animal Response Team