As it would appear from the image below, someone is about to receive training for the Nexus S 4G. On top of that a launch date of April 18th has been listed, although nothing official has been said as to whether or not this is true.
While we don’t have “official” availability, prices have already been released for the device. The Nexus S 4G will be offered for $199 with a new two year contract and users wishing to use wifi hoptspot will have to pay $29.99 a month to make use of the application. Hide and wait, if this rumor is true, Sprint will announce it soon.
Source: Android Central