Haha. I feel very silly now. I was just about to respond with the same thing.

    while True:
        result = list(islice(iterator, 3))
        if not result:
            break
        yield result

That's what I did, I edited my post above. It's around 23x slower, although I had to use a function invocation for %timeit as well, so it's probably a bit faster in practice.

One more for kicks:

    n = iter(array).next
    [(n(), n(), n()) for _ in xrange(len(array) / 3)]