I'm an overseas 56K modem user from Australia, and I have no problem with downloading large files from the internet - I just use getright or similar proprietory system, like fileplanet uses ( I subscribe to gamespy and gamespot)
500MB only takes about a week of leaving your computer going while you sleep - and lets be serious here: A week is not a problematic distribution time - its at most a few days longer than the very fastest postage. But more importantly - it can be months *shorter* than the slowest postage!
To cater for those who desire physical package goodness, I suggest that Telltale have their game cover illustrations available on CafePress as lunchbox graphics, and voila, an instant game box!
On a more serious note, if enough games companies (and there are lots trying to avoid packaging) suggested that Cafepress (or similar company) add a "two piece box" piece of merchandise to their list of products, then everyone would be happy.
my 2 cents.