Memory will go down overtime my friend. The 8GB (4GBx2) just last december was $899 and sometime last october it was $1000.
I'm pretty confident that the current price of $349 will drop to $249 or $199 just before they prep the 8GB dimms to be released.
I remember 2GB sticks were about $300-$400 a pop, now you can buy 2GBx2 for a total of 4GB for $99-$150.
The new unibody 13", 15" and 17" (the model I have) supports up to 8GB of RAM so no worries.
I just dont want to drop $400 right now for 8GB because I dont need them THAT bad. But if it hits the right price, I sure can use the 8GB of RAM. It'll actually give you a little better battery life as the RAM wont page out as often and put less stress on the hdd.
All I can say is for those people that spent $1000 on the 4GBx2 (8GB) just a few months ago has to be kicking themselves now!