A new software update was rolled out to my Lumia 800 device. This new software updated the phones firmware revision number to version 1600.2483.8106.12070.
The most viable improvement this new update brings is to the battery performance. I have done diagnostics through the build in tool and found out that before the update the discharge rate of battery was nearly double compared to after the update. My phone is now lasting more than a day with no change in usage. Before I could barely meet the end of the day where the battery would drain out.

How to check the current discharge rate?
Here the mA rate was always like 280-320 mA (40+-). After the update the rate averages to 90 - 120 mA (20+-). This rate however spikes for few seconds if I lock the screen and then unlock it. So it varies upon application usage. However before the update it was always high. This means when the phone is in standby it is now consuming less battery.

I am getting the above values with 9 background agents running in the backend (max for Lumia 800), over 30 apps installed, push settings for exchange account, brightness set to auto plus some 4-5 email account which check for new emails every 15 minutes or so.
Also there were some other bugs which were introduced with and some bugs which were never fixed after the Lumia battery fix update. I can confirm these are now fixed with this new update.
This is one of the reasons why I upgraded to a Nokia Windows Phone from HTC. This is the third update I received for my Lumia from the last 3 months. I am definitely looking forward to the Lumia 900.