iOS 4.2.1 was released today. I upgraded through iTunes on a Windows machine. I had a problem that a lot of people are having though, where all of my songs are missing. So, the workaround that other people are using involves the iTunes that you normally sync your music with. Obviously I sync my music with my ubuntu, so that doesn't work.
I came home tonight and my computer isn't even recognizing my iPhone when I plug it in. So now I've got an iPhone with no music and an OS that's oblivious to it. >_<