i wanna tell u about some shit here, ppl don't seem to understand.
1) i heard about a method, that used the fact that u know how u have folders uswest europe bla bla and char names on it? well some dude (not gonna tell who) told me that bnet once used this for backups if a game crashed, so if ur game crashed and u edited ur char the game would check the file and get out new items from the backup. this actually sounds reasonable... dunno.
btw, the uploading method morg tells about is actually simple, u just get a char from open, and use a packet that u usually enter a game on closed bnet with,and u enter the game, give the items, do this again and again. this was probably hard for blizz to notice cause they made it look like someone was just entering a game. the dude who found out about the method, later told blizz about it. he discovered this on his private server which he used for testing.
O btw, another thing. Most ppl don't remember this,but there was once a legend called Root. he was the ONLY one to gain full access to bnet, and just do what he wants with it.
he practiclly hacked bnet, i don't think anyone could do this again.