Have you been waiting for the bug fixing update that Sprint was rolling out for the Nexus S 4G on July 11? You should stand down as something has forced the carrier to postpone the update until some unspecified date in the future. No reason was given for holding off on the Nexus S 4G OTA update, unlike the one for the Samsung Transform that began rolling out but "was failing" before cancelation. That one will be rescheduled for some point when the update will actually work.
The Nexus S 4G update will bring the flagship Google phone to the latest version of Gingerbread. More importantly the update addresses signal strength issues that some Sprint customers have reported affecting both phone calls and data connections. Hopefully it won't be long delayed for those customers.
These update problems demonstrate once again how poorly the Android update system works. It's never known which phones will get a given update, or when it might happen if so. Now we have a couple of handsets that are to get an update which gets canceled for reasons unknown. It is not a simple process for Android handset makers, that is certain.