1.5.1 Update is live!It's a big update, not only in what Mojang has added but also plugins and worlds.
We also "celebrated" in a stranger way:

PearlXP:Works once more, and just like it always has. Left-click an Ender Pearl to imbue XP into it (up to 825XP, or enough to go from Lv0->Lv30). This will turn to an Eye of Ender with Aqua Affinity enchant. To retrieve XP, left click that and it'll revert to a pearl.
Shopkeepers:Installed to facilitate player exchanges, and increase the value of emeralds as a currency.
Here's how to make a store (more details
here):

<1> Purchase a Store Creator (really a modified clay ball) at the admin stores, or from another player if they have one. New ones will have a Power 1 enchant as a proof of authenticity.

<2> Right-click the air to select the kind of shopkeeper:
- Normal: sells items. Emeralds only.
- Trading: Trades items between players. Supports anything.
- Books: Sells books. Haven't gotten it to work well.
- Buying: Buys items from other players.
Right-click when sneaking to choose your shop type between villager, sign, or witch.

<3> Place down a chest, and right-click it to link the future shopkeeper to it. Then click the block you want the shopkeeper to spawn at. (Make sure to protect your chests! :V)

<4> To adjust deals, place items you want to buy/sell into the chest (if selling, put at least one if the items you'll accept in there). The chest contains your supply of items, and will take in goods that are exchanged.
<5> Pricing can be adjusted by right-clicking the shopkeeper while sneaking. The top row shows your deals, and bottom two are what players will give. Anvil sets shop name, wool block will change villager skin, and fire will remove the shopkeeper and return you a non-enchanted Store Creator.

Normal shops will have slimeballs in them. Left-click to raise prices by an emerald, right-click to lower.

Trading stores instead accept 2 items for exchange you can put in. Note that it'll put down your entire stack or part of a stack at first - you can later adjust this via left and right-clicking.
So going back to above example, I put in my entire fish and stone supply, resulting initially in this:

As it relies on player supplies, for those with active stores remember to check your supply.
I will also ask that all shops have a name for the sake of identification.
Miscellany:Mere updates and the Rebalance Villagers plugin. That is all.
World information:We have a
brand-new Nether, End, and AdvWorld 1 for all to enjoy. I take no liabilities for losses.
WARNING: Using the spawn Nether portal to return has resulted in new Nether portals sprouting on main world. Make sure to
warp out to prevent this from occurring.
AdvWorld 2 in the meantime....
BIOSPHERE 2: REVNANCHIST PLANETOIDSThose who were on DDR's server in summer 2011 remember this unholy abomination called Biosphere. All land was in spherical formations floating above insta-death bedrock, meaning that perillous bridges were everywhere and mob spawns concentrated in the few patches of land that existed.
It has returned, but this time we have planetoids for biospheres.
Each planetoid has an outer material and a core with something else. You could strike it rich...or face a miserable/blissful death. Tread carefully....

EDIT: I think one can strike it
too rich here; I'm considering a nerf, but more likely this world will not be on for too long.
EDIT2: New less-exploitative version arriving later.