Glad others are enjoying Minecraft, especially Multiplayer. The gaming community that I manage the servers of (TrashedGamers.org) has had a Minecraft server in one form or another since Sept. 2010, but we stopped for a few months when Beta came out due to extreme lag. As of April 2nd, we tried it again with Beta 1.4, and since we were happy with the results, we rented a small VDS just for our Minecraft server (as Minecraft causes issues with Source dedicated servers for some reason, even though the server hardware isn't being taxed). We've always had a lot of fun building our creations and such together.
Here's our first topographical map after 8 days if you're interested: http://maps.trashedgamers.org/TGMinecraft4102011.png