yeah but you really need to kick it in order to get it off.If the force is big enough to yank off a magsafe cable, it should be good enough to yank off a USB plug. The question is do you just want your data to die, or you want your USB port to go with it?
using magsafe for a few years now, never really had it accidentally disconnect.
Also the magsafe/Light Peak cable you see will probably be used for connecting between machines (macbook) and monitor (Cinema display/iMac).
Just like when apple made USB standard on all macs. There were no accessories, everybody was either using ps/2 or adb. Everybody (apple haters) claim that it's apples plot to get all the stupid Mac users to buy their overpriced USB keyboards.
So far no one can create any notebook with the build quality of a unibody macbook.And magsafe is still the most advanced power connector on the market.They are already way ahead of the competition, but it's good to know that they are always looking for something to improve on.