DC, QChat sounds great and is true. As far a Nextel goes there has been a letter issued to government accounts stating that the network will not go off-line (the letter sounded as an 3-5 year outlook, not forever). During the merg agencies were wondering if the network would survive, had complains and started contracts with various providers. The letter was a simple confirm that things would keep working and get better. However in some regions service is not considered acceptable and resolutions are needed. There was a release in October i believe stating that Nextel would be using QChat. I can say that handsets have been tested. Your area will need EV-DO and look for more info late 07 early 08.
Here is the release for QChat, i can't post the other mentioned letter. Sprint Nextel Teams With QUALCOMM and Lucent Technologies to Extend Industry-Leading PTT Services