I think the most important thing now is a working Sponge Mod for Forge. But it was also said that there will be a standalone Sponge server based on Glowstone.
Glowstone is a direct implementation of the Bukkit API. That means, if you want to make a Sponge version of Glowstone, you have to rewrite a lot of it.
Glowstone is a nice reference (and not closed-source, like Mojang’s code), but I think starting from scratch would be better. How do you want to do it?
I would like to help with the standalone server. I don’t want to rely on Mojang anymore.
I think that glowstone is being rewritten from scratch anyway, plus only the api portion of glowstone was based on bukkit, the server was their own creation.
Glowstone is a from-scratch minecraft server. If this project, which is still far away from a fully functional build, gets to a point where they can keep up with vanilla that means that sponge will have a redundancy in the case that something happens to MCP or even forge. In a case in which glowstone is 100% working it would be great for sponge to have an implementation of it as it would basically be a fail-safe for the whole forge side of things.