As has been the practice with Nokia recently, when a firmware comes out for one device, a few others get new firmwares too. After the N97, the N96 has been blessed with the v30 firmware. This release is a 6MB over the air download and makes the device faster and fixes a few bugs. Nevertheless, it is good to see Nokia not neglecting an old device which failed to take off.
The new firmware is available over-the-air (OTA) by simply pressing *#0000# from the standby screen and checking for updates. (Detailed guide on how to update OTA here). The phone features user data preservation (UDP) so your data should be fine even after the update, however a backup never hurts. The update should also be available via the windows only Nokia Software Updater.