ENUM 164 isn't just some obscure protocol, it's an international standard and has been implemented by many providers. e164.arpa, managed by RIPE has been in testing for quite some time, and commercial providers have also come into existence recently to take advantage of the protocol and build out their own niches.
Although it's supported, ENUM's full capability isn't going to take off without software that support it, so here are some resources for developers who are looking to implement ENUM 164, especially support for E164.org into their products.
[http://www.faqs.org/rfcs/rfc2915.html RFC 2915]
RemoteManagementProtocol : The E164.org remote management protocol for updating NAPTR records remotely.
LibEnum : A C library that implements ENUM resolution.
[http://www.e164.org/enum.phps enum.php] : An AGI script for ENUM resolution (works around Asterisk's buggy EnumLookup application).
[http://www.voip-info.org/tiki-index.php?page=Asterisk+and+multiple+ENUM+entries enumlookup.agi] : An AGI script for enhanced ENUM lookups
[http://home.arcor.de/benno.kroeck/enumlookup/index.html] shell agi script for better lookups.