*UPDATE* - Check out this post in the forums for the exact details of what this is. It uses official files but no installer was given so one had to be created. You can decide for yourselves if that makes it official or a Hybrid.
All of you BlackBerry Bold 9650 owners out there will be happy to see that OS 188.8.131.521 has leaked for your devices tonight! Word has it you're likely looking at bug fixes and minor app updates in this one. If you were waiting for a new OS for your 9650 or if you are a hybrid builder, you can download it from the link below! Let us know in the comments what fixes you see if you choose to install this leak. Take caution however, you must have OS .333 or .415 installed before you can upgrade to .431 as noted by the source.*OS Disclaimer - Please Read: Keep in mind this is NOT an official release and as such is not supported by RIM or your Carrier. If you choose to install, do so at your own risk and only if you're comfortable in the process of upgrading and downgrading your device software. It is quite normal during operating system development for certain features to be crippled or disabled while others are tested, and these beta builds often reflect that. They are not always better. Depending on your BlackBerry comfort level, it may be best for you to wait for community feedback on a build before deciding to download and install for yourself or simply wait for the next official release. If you require support, you will find it in our CrackBerry forums via our extremely knowledgeable community base - do not contact your carrier or RIM for Beta OS technical support (their first course of action will be to advise you to downgrade to a supported OS). *