Can I acquire multiprocessing's Lock in a with statement?

Yes, you can just do:

with multiprocessing.Lock():
    ...

as Lock is a context manager. So is RLock, and Lock and RLock from threading.

The documentation does state that it is "a clone of threading.Lock", so you can refer to "Using locks, conditions, and semaphores in the with statement"

[edit 2020: The documentation now mentions this explicitly]

Yes you can.

The documentation for Lock states:

class multiprocessing.Lock

A non-recursive lock object: a clone of `threading.Lock`.

Reading threading's documentation:

All of the objects provided by this module that have acquire() and release() methods can be used as context managers for a with statement.