I'm not sure i trust that website entirely, seeing as that seems like a lot for 3GB, and i found it in the Minecraft forums, but hey, you never know, and if it is correct, it could be pretty useful.
Aye, that is download/upload in Megabits/s, or 8/1.2 Megabytes per second.
I did take a look at that site and from what I gather, upload speed will be the limiting factor. But it doesn't take the cpu into consideration, so it feels a bit whimsy.