If I remember correctly the player name is concatenated to the password. You should be able to read this in the source code. I don't have the source on this PC so I can't check.
your web service doesn't allow dns names instead of an IP address. I sometimes run a server at home but I have a dynamic IP address so I use a dynamic dns service.
I made some minor optimizations, it's about 7% faster or so, and some other changes. I have considered porting it to C, but I need to know better what the python script does before I start.
I like your torches and your player (though the player texture didnt load @ my computer for some reason). Some of your textures look a little 'bland', I think. For example it's hard to tell the difference between planks and sand. Wood could also use some additional markup. I like your cobble stone, ...