Victory!

After 5 hours of scrubbing, and 3 Costco sized tubes of toothpaste... the giant permanent marker wall-murals have been erased! And our apartment smells minty fresh. :) 

Things I learned about permanent marker:
It is evil
The red ones are even worse
Toothpaste is the only thing that worked to get it off, not rubbing alcohol, not baking soda, not peroxide, not the "magic eraser". Plain old regular toothpaste. Not the gel kind...
You have to have a bucket of water.  Toothpaste dried onto the wall is not easy to get off... you have to get it off before you can get to scrubbing the marker off. And you need to rinse the thing you are scrubbing with, because the toothpaste gets all caked on...even when you've got a good foam going.
You don't use an old sock, or a washcloth.  That was a total joke... :P  Steel wool, my friends, steel wool!
Rubber gloves are good, because as I found out, steel wool + scrubbing + toothpaste + bare hands = very white pretty nails, and very sore hands. (I know this is obvious, but I didn't have rubber gloves lying around... so I thought I'd try before I made yet another trip to the store... lol.. don't do it!)
Scrubbing Permanent marker off of walls for 5 hours is a hardcore arm/back workout, so I will count that as a positive. ;) 

Lastly, I learned that my little artist was sweet enough to get his little sponge, and help mommy clean up his "picture".