Finder in Snow Leopard uses base 10:
http://gizmodo.com/5349516/the-real-reason-you-got-back-so-much-hard-drive-space-with-snow-leopard
If you plug in a 4 gig thumb drive it really would show up as 4 gig in Finder, isn't that nice?
However the rest of the world, unfortunately, are still...