The day has finally arrived. Beginning this week, Sprint will roll out a very limited trial of its WiMax network in Chicago and Baltimore-Washington, D.C. It is a Neil Armstrong moment. One small step for Sprint, one giant leap for WiMax's future.Word that Sprint is making good on its initial time frame -- to launch WiMax test markets by the of 2007 -- is welcome news. Sprint's WiMax venture has been in doubt with the departure of former CEO Gary Forsee and the failure of Sprint and Clearwire to reach an agreement about a previously announced WiMax network partnership.

This trial will be restricted to Sprint employees only, however, and the networks will stretch over only the central downtown business centers of the cities involved. Still, at least Sprint is turning on the switch. Sprint said it is still on track to make these test markets available to the general public some time in the first quarter of 2008, with the full commercial launch set for the second quarter of 2008. Sprint also will expand the coverage areas over time. Sprint is going to use this trial to optimize the network.

For the time being, Sprint hasn't said what hardware its employees will use to access the network. Several manufacturers, including Nokia and Samsung, have committed to delivering WiMax-enabled devices to Sprint. It is possible they have made good on their promises for this trial.

Sprint has a lot riding on this trial. It has invested an incredible amount of time, money, and energy to make this moment a reality. Sprint's 4G road map depends on WiMax to work. If it doesn't, Sprint could be faced with making some serious strategic and financial decisions about adopting a different type of next-generation technology.