The folks at Google have just released a new build of Gingerbread which is Android 2.3.6 mainly for Nexus S users that fixes the strange bug that randomly activates the voice search. This is a strange bug indeed and interferes when doing some simple tasks on the Nexus S.
However, with this bug fixed, they've broken the Wifi and USB Tethering feature. At the moment we have no further details but if you don't use the Wifi or USB Tethering and are annoyed by the Voice Search bug, you might want to consider updating it. Otherwise, perhaps its best to leave it as it is until Google sorts out with another update.