Apple has officially claimed the @Applecare account on Twitter. I know this because for the last year I had the @Applecare account.
I spent the first few days trying to help people troubleshoot their Mac problems (usually just referring them to the Apple customer service helpline), but quickly became overwhelmed with the amount of work it takes to track down all the support issues, especially when I would scan through the Twitter search and proactively try to help people with their problems. It made for a fun few nights, but I knew it couldn't last.
I'm looking forward to seeing what Apple does with the account! (If you were following @Applecare before, it looks like you've been removed and will want to refollow.)