updated 05:06 pm EDT, Tue April 22, 2014
Users must have Apple ID, signed confidentiality agreement
For the first time, access to OS X beta releases has been opened to non-developers. Apple has introduced the Beta Seed Program, which requires only that a person have an Apple ID and sign a confidentiality agreement. The agreement blocks people from sharing information to anyone not also registered to receive betas.
Once a part of the program, participants have to download the Beta Access Utility. This reveals available betas via the Updates panel at the Mac App Store.
The change could improve feedback on OS X features, since Apple normally only receives testing and comments from the much smaller developer pool. At the same time it might also engender more complaints, since betas are incomplete and potentially unstable.