Excerpt from one of those provided (for those that don't sometimes click):
"The service would allow parties to be next in line to register a domain name once it is deleted from the registry. SnapNames has customized the service to fit VeriSign's .COM and .NET registry architecture allowing VeriSign Global Registry Services to offer the WLS to all ICANN-accredited registrars. Current wait listing services, implemented at the registrar level, must compete for a domain name when it becomes available. Implementation at the registry level would provide equal access to all registrars and would result in a higher efficacy rate for applicants, as the registration is virtually assured, should the current domain name registration be deleted."