Originally Posted by
CrackBerry Storm meh Leaked OS means that they were released without consent of RIM. They work perfectly fine, but RIM found a bug in the update, or they want to continue improving on the OS, so they do not ever release it and keep working on it. Traditionally each new OS is better than the old OS. They are all safe, as long as they are not "hybrids" (Hybrids are user created, takes best features from several OS and compiles them into a powerful OS - However they are risky because they are user created)
Not quite correct. RIM produces the OS and releases them to the carriers. The Carriers decide if they want to release to the general users. If the carriers decide for whatever reason not to release, then someone from carrier may leak it or make it available to someone else to leak.
Leaks can be risky because they are not official releases for a reason, but generally they are an improvement over previous OS versions, but they can be buggy.