Uses of Python's "from" keyword?

No and yes.

According to the official Python 2.7.2 grammar, the only occurrence of the word from is in the clause import_from, so no.

In the Python 3.1.3 grammar a new clause

raise_stmt: 'raise' [test ['from' test]]

appears, so yes.

There is a new syntax for delegating to a subgenerator in Python 3.3 which uses the from keyword.

In Python 2.x, the only use of from is for the from x import y statement. However, for Python 3.x, it can be used in conjunction with the raise statement, e.g.:

try:
    raise Exception("test")
except Exception as e:
    raise Exception("another exception") from e