Is it legal to use the increment operator in a C++ function call?

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Quoth the C++ standard 1.9.16:

When calling a function (whether or
not the function is inline), every
value computation and side effect
associated with any argument
expression, or with the postfix
expression designating the called
function, is sequenced before
execution of every expression or
statement in the body of the called
function. (Note: Value computations
and side effects associated with the
different argument expressions are
unsequenced.)

So it would seem to me that this code:

foo(i++);

is perfectly legal. It will increment i and then call foo with the previous value of i. However, this code:

foo(i++, i++);

yields undefined behavior because paragraph 1.9.16 also says:

If a side effect on a scalar object is
unsequenced relative to either another
side effect on the same scalar object
or a value computation using the value
of the same scalar object, the
behavior is undefined.

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