The status updates are sent to your phone/mobile device, though. Here you are, reading news.YC, and buzz... Stephanie doesn't like what she just had for lunch. That's not a little bit intrusive?

Ummm...Do you use twitter? That is wrong. If you want updates on your phone then you can turn them on. If you don't then it is trivially easy to turn off all phone updates or set it up so that you only get updates on your phone during certain hours. That doesn't sound intrusive to me.

And... not only do yu decide if updates come to your phone, you do that on a per-person basis. So you'll only see what that friend is doing If You Want To. That's about as non-intrusive as it gets. It's entirely under YOUR control.

SMS updates to your phone is optional besides as I once "tweeted" - "brevity is the soul of tWITter"