No, my sources say its "in the pipe"
pre Hasbro WOTC licenced out their settings to Sovereign Press & White Wolf.
Hasbro wanted to take the ummm opportunity to bring them all back in house with 4e. It would appear that Dark Sun is the first one to get some treatment on D&D Insider. If it does well the plan is to release a 3 book set for Dark Sun. My understanding is that all the old worlds will get a similar chance and becoming a 3 book set. I believe Spelljammer is next in the pipe but Dragonlance and Ravenloft fans are just going to have to wait for their turn.
Running: infrequent VtM game
"I'm beautifully hideous!" - Sven the Nosferatu