I have been asked for my UDID, is there any personal information that will be given away should some have this number?
Your UDID can be used to uniquely identify your iOS device. The UDID is often used to associate actions with a specific known user. Using your UDID, developers' may be able to associate your actions and use of their app back to you.

Apple associate private information with your UDID. You are required to trust that Apple  keeps this information private. Hopefully Apple will not sell this information or have it leaked through a security breach. While not highly valuable, if you have privacy concerns consider avoiding participating in beta apps programs.

ArsTechnica has a useful article that discusses the relative risks and uses of the UDID, Ask Ars: What’s the big deal with iPhone UDIDs?