Could you add support to create portals to work the same way as signs?

I have been asked that before and I'm not really fond of adding a whole other functionality into the plugin (as portal handling can be a bit annoying). I will think about it but for now you are better of using WorldGuard-Regions with a flag to execute commands on enter from a plugin like WorldGuard Extra Flags or similar.

This could be implemented as an addon by using the newly appearing API.