The plugin mentioned above is mine. Hope it helps, I was just as disturbed that all that data was being sent to Akismet as everyone here apparently has been.
I have to say, I'm somewhat disappointed in Matt's response here. I'd say we're certainly trying to incite something: an explination. From what I've read (here, as well as other places) that's been the key goal all along: to learn why this data was being sent in the first place.
I'm sure people whould have had much less of a problem, had you come out and explained why the entirety of $_SERVER was being sent with each request (either that it was a mistake, or that it was needed for <reason>). As with most things, when a question / complaint goes un-answered or gets brushed off, people start to wonder if something's being hidden or if there's some ulterior motive.
As for the legal statement... Privacy policies are great, but it's the human touch that we all crave. You're *the* Matt... If you'd just told us it was a mistake, or assured us that it wasn't being used nefariously, most of us would have nodded and trusted you because we have no reason not to.
Maybe we can all learn something from this, eh? :)