The OP should have first gotten a lawyer to look over it, instead of freaking out hysterically here.
He's not being sued. Twitter does own the name Twitter and can selectively choose to sue/C&D (or not sue) anyone they like who infringes on it. You defense being "other people have registered the domain names too!" isn't any better one than you'll get with saying, "But other people use Bittorrent too!" Someone up in the thread said, "No one can now use the Twitter API" because it says you can't use Twitter's name in your application, but they want you to put "Powered by Twitter" on the site. That's just FUD. Come on guys, put on your big boy pants and lets show a bit of business acumen and maturity here. Twitter isn't draconian, shutting down the developer community, etc. That's just silly.
