As far as I know this marks the first official release of OS 6.0 for the BlackBerry Curve 9300. Starhub just released OS 188.8.131.520 which we saw leaked before and has now been made official. This release was pretty stable according to reports on the leak so it should be pretty safe to install on your device.
Kudos to the BBNews.pl team for spotting the release and Tashanna for the tip!
Warning: This OS will not install on any other BlackBerry besides the one mentioned above. Don’t forget to delete the vendor.xml file located in c:program files>common files>research in motion>apploader to install it on a different carriers device. If you do not know how to upgrade your BlackBerry OS please start by reading this step by step guide.