It appears as if BlackBerry Messenger 188.8.131.52 is included with the latest Bold 9700 leaked OS, and BBHybrids has posted an OTA link so everyone can get in on the fun. Rumors all over on what is new/different in this version (dive into our forums for lots of threads on it), but if you want to give it a go you should be able to install it on any device running OS 5.0. We're not sure how long the link will stay working, but you can give it a shot and keep your eyes out for any download mirrors that will likely pop up. Be sure to leave a comment and let us know your findings.
* Disclaimer: Same standard disclaimer as all OS leaks apply. Install at own risk. *