Google Buzz: bzzt!
A third decision was unambiguously (IMO) bad: they made it opt-out instead of opt-in. I am having trouble thinking of a single case where it would be a good idea to automatically, and without notification, make changes to existing accounts. [Edit: I meant good for the customer, and not counting things like "hey, we gave you more disk space". I mean new behaviors.] Auto-on for new accounts is quite defensible (with documentation); changing the behavior of accounts that people set up on the basis of a different implicit contract, no. Especially if you haven't previously sent out an update to your privacy policy.
There's one more problem with Buzz: opt-out doesn't really work. If you do the obvious thing and click on the "turn Buzz off" link, all that does is remove a shortcut. Your connections are still there. That's just bad engineering.
Google says they have heard the feedback and will fix things in a few days. And, while I can't verify this without a second account, some people believe that deleting your profile keeps Buzz at bay. [Edit: confirmed with the help of another gmail user, thanks.]
Buzz could, potentially, be a useful tool, though it remains to be seen whether the world really needed yet another attempt at a social-networking site. But their roll-out of it has left a bad taste in my mouth, so I'm likely to wait a while, until I hear positive reviews from people whose opinions I value, before I touch it. And I'll have to be certain that they aren't publishing information that (otherwise) exists only in my mailbox. Linking to my public Picasa album is fine; it's public (same as the vast majority of this journal). Telling the world who I correspond with and how often, however, is not.

no subject
I hadn't previously attempted to filter them out, but just now going and trying to find a setting for it I could not do so. (There's an option to not hook up my Twitter account, but the obvious place for filtering other people only gives me an "unfollow" option with no finer granularity.)