Notch has announced on its official blog that the next beta update 1.6 for Minecraft will be coming out at somepoint next week. This new update will feature some new maps and also lots of bug fixes.
Notch wrote on its official blog: Oh, and 1.6 is coming next week.
The developer also commented about Nether in multiplayer, which is one of the bigger fixes, he explained that I can move back and forth from the normal world to the nether in SMP as many times as I want now. :D