Folks, my company just released an updated version of the SIP stack and UA (MJSIP) ported for the latest SDK 1.0r1. This is the same SDK that G1 uses. This is an update to this post.
The new SDK changes several things in the UI and well as some APIs. Kudos to the team lead Nitin Khanna (first.last at hsc.com) for continuing the commitment to android.
Grab a copy of the latest version from here.