Yes there are really small updates to 2.3.7
Released on 25 July 2011, Android 2.3.5 included a number of system enhancements:
Improved network performance for the Nexus S 4G, among other fixes and improvements
Fixed Bluetooth bug on Samsung Galaxy S
Improved Gmail application
Shadow animations for list scrolling
Camera software enhancements
Improved battery efficiency
Released on 2 September 2011, this version fixed a voice search bug. The 2.3.6 update had the side-effect of impairing the Wi-Fi hotspot functionality of many Canadian Nexus S phones. Google acknowledged this problem and fixed it in late September.
Android 2.3.7 introduced Google Wallet support for the Nexus S 4G.
And I've noticed several apps are higher than 2.3.4 in stock rom while it says it is 2.3.4 so I think that important things are included in last stock release