While Bukkit has not realeased any 1.7 versions yet, Bukkit‘s competitor, Spigot, has released a (buggy) pre-release version. I am using this currently to generate a new Empire world. Once that is finished, I will look at the world map to judge if the seed is appropriate to be used. If not, I will start from scratch. If it is suitable, I will publish a map image with the lots overlayed so people can get a first impression what their lot will look like in case they reset. One risk is that the current 2D renderer cannot deal with some of the new biomes like mesa etc. We will see how we deal with that.
By the way, I will allow people also to chose a DIFFERENT lot than they have today if they want to abandon their current one (provided that the target lot is unused), on a first-come-first server basis. Details will follow.
Regarding Spigot: Aparently spigot is better to deal with lag on the server and run all the plugins that bukkit can run. So I will make a try to switch to spigot, if that fails, we just stick with bukkit.