It’s great to have people checking over the auto-linking issues at last. The http://www…foo issue was reported at http://github.com/mzsanford/twitter-text-rb/issues/closed#issue/4 and has since been fixed in the Open Source library and is awaiting deploy on twitter.com.
It turns out to be a harder problem that expected. The http://www…foo bug was introduced while adding support for some IDNs. I’ll investigate the TLD stuff but the main worry is the gTLD process and what that will mean for the list of valid TLDs.