I turned my girlfriend Anette onto Twitter 6 months ago (@anetteherrera. She's admittedly and proudly not a techie; but she enjoys following a few close friends has actually posted 100+ tweets since registering.
All of her twitter usage has come from her Blackberry. Other than registering, she has never visited Twitter.com. So when she asked me last night why she hadn't received any Twitter updates in over two weeks, I realized that she had no idea that Twitter had been down and shut off their IM service.
Twitter has been lauded for being transparent with their status problems - releasing a new blog, giving interviews and attempting to address the issues. But, that praise has come from techies (like myself). And if you don't read TechCrunch or blogs like this regularly - you'd be left in the dark wondering why firstname.lastname@example.org on GTalk isn't working... which is precisely what happened to Anette (though she really should read my blog!).
The lesson I learned is that transparency only works when there are viewers.
One of the great growth factors for Twitter was the ability to receive and post from distributed sources (ie off-Twitter.com)... But the only notice from Twitter regarding their service failures is on a status blog and in a small square on your Twitter.com profile. Perhaps an email would work? Perhaps an @twitter direct message?
While most of Twitter's users are tech-folks, I guarantee there are countless others like Anette who wondered why they weren't receiving Twitter updates and couldn't makes posts. It's not good business to hope that these users figure out what's going on and hope that they return... when the service returns.