Minecraft 1.6.4 is the current version of Minecraft as of now. With Minecraft 1.6 came over 100 bug fixes, the addition of hatches, tall grass, dead shrubs in deserts, the elimination of glitched minecart boosting, and the addition of the playable Nether in multiplayer and many other things. Along with the intentional changes, however, came many unintentional bugs. Notch and Mojang attempted to rectify the situation with multiple patches in one day (1.6.1, 1.6.2, 1.6.3 and 1.6.4). Unfortunately the patches did not solve everything and several bugs such as: spawning in midair, having partially damaged items break after one use if they had previously been dropped, severe lag in multiplayer, and lighting problems persisted.
Due to the enormity of the bugs Notch will be working on them on Saturday, which he definitely does not have to do, and he should be commended for this. As the game is still in Beta, and being improved for the eventual release in November, bugs can still be expected and should be prepared for. I would advise everyone to make routine backups of the .minecraft folder, before updating. By having a backed up copy of .minecraft, you can revert to the previous version if the newest release is overly bugged. By backing up my files, I was able to, for instance, recover my record from my jukebox, which due to a bug in 1.6 was deleted. I simply deleted 1.6.4, returned to 1.5 with the backed up save, and updated to 1.6.4 again with the intact record.
Minecraft is a great game, but it can be jittery, especially around update times. Though Minecraft can lure you into false sense of security with it being stable most of the time, remember it is still in Beta. Be sure to backup frequently, so that your hours of work and fun are not ruined.
