I'm speculating, but I think the policy changes are a done thing, drawn from the bi-partisan Iraq study group, and that Gates was pulled from the group to implement them. We'll know within the week.
It's a good speculation.
Many don't like to hear it, but SecDef's don't last 6 years. They last about 2 or 3 and an occasional 4. Rummie had a great run. There's no reason for bitterness OR for thinking that he's the only guy who can make it happen.
He would have done himself a favor by departing at the 4 year mark. That's what I like about the guy. He stayed, realizing that it wouldn't help his legacy at all.
He had guts, and he deserves credit for that. And, IIRC, he was the one who moved Tommie Thompson off the dime in Afghan...pushed him to sh_t or get off the pot.