Bukkit

Added a new config value which adjusts the population density for future regions. Use a lower number to reduce population density, spreading players farther apart, or a higher number to add more players to a region before moving on, which increases the density. Prime recommendation - leave this config value at the default for a long time before you go fiddling with it. The default was very carefully chosen based on lots of real server data.

Very small adjustments (0.2) at a time are recommended, and will make a huge difference. It takes a long time to see the effects, because lots of players have to join your server and build, enough that a region is automatically closed, before you can look at the closed region and decide whether the population density you're seeing is what you want.

Added an option to disable the "welcome to X region" and "player has left/arrived" messages.

Added a possible fix for the "end portals in the managed world don't work" problem. I can't tell for sure - the current issue I'm experiencing is that I get teleported to the end, but in the void, and die. I can't be certain whether it's a general "extra end worlds" issue, or an issue the Bukkit guys are working out of the CraftBukkit builds right now. Anyway, the end is way overrated, and the only way your players can access it is if you update your config to allow them all to build and break everywhere. Hang in there for a new recommended craft bukkit build.