First off, I'd prefer it if no one posted on the Dragon's Gate forums about Shattered Isles until the creators are ready to make that announcement. Word has spread through the old Dgate community, but this is a card we'd like to play later on and one you can't play more than once or twice.
Secondly, if you are playing another MUD, do not post an advertisement or endorsement for Shattered Isles there. That's just bad form. When I first heard about a post on the Aedin Info board I was terribly disturbed and went over there to respond directly. When someone took it a step further and posted on their main message boards, I felt awful. This is just disrespectful to do as each community is in a fight to keep the players they have as well as attract new ones. We would not take kindly to someone doing it here, so approach other games with the same respect.
Other than that, just be sure to share a link to the main website rather than giving the game login information. It's always helpful to read up on things some before diving into something new. Be sure to let others know about the current state of the game as well.