NoCatAuth is the CaptivePortal that is being developed by the NoCat group. It is in beta right now, and will support having an open system with configurable restrictions to bandwidth and ports based on if the user is a trusted member or not. --MichaelCodanti
There was a some SlashDot coverage as well. Way to go guys! -- AdamShand
A successor written in C is in the works, suitable for embedded-style applications:
See also: NoCat, NoCatAuthWishList, NoCatAuthTesting, NodeSplashPages, NoCatAuthWorkFlow