I know that before it was not possible with hey0 mod but will there be a way create a portal to teleport to another local server (like switch between survival and creative). Inventory should not carry over but its something that I always wanted to have for my setup. The far I have seen a plugin has gone to create one was it kicked you and told you the IP address. Also another idea is that I would like to partner with other servers to "link" them together and make them like "mineports" (get it?) to the Minecraft Universe. Would be AMAZING! Will there be hope?
The only way to allow a seamless portal to another server is through client modification, which the hey0 plugin you are referring to has (I think, I never used it myself).
Yes, cross server teleports would require the client to support it more than the server. However, I believe that multiple worlds per server are an idea and notch will probably be implementing it for the nether.
The question is if you can control what commands you can do within each world. Still would be cool but I would love to find a way to. Maybe a plugin can help with that since we cannot have true server to server portals.
We know that, What Chad wants to know if Bukkit/Craftbukkit will deem it possible to-do so without a update from Notch.
i know hmod had it via plugin (Server Port), but to have it work seamlessly you needed a client mod as well
if you allow switching worlds, you could add hacky inter-server communication by having them proxy each other likely to be laggy as crap, but should be possible to an extent. Note: it's 5am, if this all sounds like nonsense merely ig-ZZZZZzzzzzzz-*thump*-nore it.