A Nokia employee over at the official Nokia Discussion forums just posted a heads-up about a new update being rolled out to Asha 306 owners:
We have started rolling out a new software update for Asha 306 (RM-767 & RM-768): v. 5.93. Based on current information this update will be available mostly to users in Middle East, Africa, South East Asia & Pacific regions (including India) and also some users from Latin Americas. The update should be already available via Nokia Suite for many countries on the mentioned regions. FOTA update packages should (hopefully) follow later. You can find the update instructions for your phone from here.
The latest update brings some stability fixes, performance fixes and some all around general tweaking:
Key changes compared to previous 3.63/3.81 SW versions:
Phone software stability improvements
Improved display brightness and touch screen performance
Improved phone memory handing
Correction for the Taipei time zone
General performance and usability improvements
I was actually surprised to see that the S40 devices support over the air updates, which is quite impressive; seeing how it only became available to iOS and Windows Phone users quite recently.