To break it down, Bukkit is going to exist no longer and its major team will be working on the Minecraft API, which is for both servers and client modification. 1.2 or 1.3 will break A LOT of things for us in the way of server plugins. We will most likely lose some old plugins as the developers of those plugins are inactive.
What does this mean for us in the future?
We will have to go through and figure out which plugins are not going to be updated to work with Minecraft API. No, Bukkit plugins will not work with 1.3, only 1.2, per Jens (jeb_) on Mojang's post. We are looking to move forward with Spout in the future to help out with a lot of client and server mods. For example, a Spout version of Mo' Creatures, along various other...
Welcome to Era! Here is a list of the changes that will affect you upon moving to the new map, Era.
First, your items and home are not lost! You can do "/home" once you have went through the Tree in Era.
All new people will spawn in the tree in Arhi.
You will no longer be able to do /back upon death! Better make sure you have a chest on you if you don't want your items to be lost when you die!!! They will not be replaced.
When you die and if you have a chest on you, a chest will be placed with your items in it and be locked so only you can open it. The chest will have a sign on it with your name. You can right click on the chest to get all of your items back - this will immediately put your items in your inventory. After 25 minutes of your death, your tombstone will be unlocked for anyone to claim. After 30 minutes of your death, the tombstone will disappear! Always try to be aware of where you are so you can find this chest easily!
We are aware that 1.1 has come out. Do not ask when we will update as we have to wait for CraftBukkit to update to the new version and then we have to ensure our plugins will work with the new version. This sometimes can take weeks. DO NOT UPDATE YOUR MINECRAFT!