We now have a more concrete date on Minecraft patch 1.6 going live, instead of just "next week." Notch tweeted early this morning that the patch is scheduled for a Wednesday release. He follows that up with stating that this more than likely means it will be released late Thursday. But still, we at least know the day(s) it's coming now.
He also shared more details on the bug fixes in the patch. There are 78 lines in the notes for fixes and tweaks for the patch as of this writing. Notch clarifies that these are mostly minor bug fixes, including things like fixing dispenser graphics being one pixel off. But he's also nerfed fire: it will no longer spread infinitely as of the patch.
There's also a new server view-distance property being introduced, allowing admins to choose the radius of terrain updates -- in chunks -- that are sent to players. You can tweak this anywhere from 3 to 15, with the default being 10.