Doorway pages are not necessarily cloaking though. I've a writeup on it.
"There is no such thing as White Hat Cloaking." - Matt Cutts
If by monitoring your keyword traffic you see that you have landing pages that will better serve your visitors then the ones they are landing on, then it is a right of yours to redirect the traffic to a more proper location.
There may be no such thing as white hat cloaking, but there is such thing as white hat traffic management. If we allow the Googlebot to pass along side the visitor with a targeted redirect, then both agents are shown the same end result. Google might even take our advice and rank our redirect location above our original landing location.
Still there exists all kinds of Grey Hat cloaking, which, have their valid sentiments and represent a contention of wills between site developers and Google. There is no clear winner of right and wrong, that's why it's called Grey.
And there are even still Blackhat cloaking practices that can be represented over a continuously degenerating scale, ending up with the reprehensible example Matt Cutts gives us in the opening explanation of Cloaking. Yes, thank you Google Spam Team for existing and addressing these issues for us. You are appreciated.
But I want to effectively separate the idea of traffic and human+spider management from the idea of cloaking. If you show the spider a different thing, you're cloaking, but if you send the spider along with your human traffic, you're optimizing.
In other words, it can't be said that there is no such thing as a White Hat doorway page.
Here's the video of Mr. Cutts talking about cloaking.
http://www.youtube.com/watch?v=QHtnfOgp65Q