Apparently, Jelly Bean is already rolling out to the Nexus S in Pakistan. A user over at XDA just received the OTA update earlier this morning. This likely means that they will be pushing the update out to the Asian regions first. A download link from Google was provided for the update, so if you don't feel like waiting for the OTA, then you can get it started now. Here's the link below. Let us know if there are any problems.

JRO03E Update

Source: XDA