Apple announced a new 12" MacBook. The only port other than a headphone jack is USB-C. Since it is new technology I do not have any USB-C memory sticks.
What adapters will let older USB sticks work with this port and Mac?
Simple answer - yes.
Apple has also announced an USB-C to USB connector for £15 in the UK store or $19 in the US store.
It too isn't shipping yet, so it's hard to know if this is a custom chip and design or any old "connect the wires" adapter will do the trick. However, my guess is that it's just a simple adapter and there's no licensing like the lightning port requires/allows.
The specifications are that the port is just USB 3.1 Gen 1 which means that pretty much any USB-A device in existance will interoperate with the new MacBook.