We understand that with the upcoming release of iOS 5, there are probably plenty of iOS users and a few other interested parties who are curious about what the latest incarnation of iOS 5 will bring to the table. Developers who had access to the betas of iOS 5 probably recognized that there was a market for the betas, especially for early adopters, and have started selling their UDID slots.
Apple is probably not very pleased with that as they have started tracking those developers down and have reportedly sent them emails warning them that their activities have been discovered. There have also been reports where developers accounts have been closed for selling their slots, and even flagging UDIDs associated with a developer account that has been found to be in violation, therefore rendering the device running iOS 5 unusable.
Given that it is a public beta, the developers were probably not bound to an NDA (non-disclosure agreement) given the amount of iOS 5 beta coverage, but they were probably given a set of terms and one of those terms most likely consisted of them not selling or giving away the beta to unauthorized users.
If you’re curious about the various features about iOS 5 it’s best to just stick with the news (such as our blog!) instead of paying for a beta which is more than likely to be filled with bugs, and will probably not deliver you the iOS 5 experience that Apple had intended.