I'm gonna hijack. I have another thread running about this but it can't hurt to put it here too.
I updated my iPhone 4 to 4.2.1 tonight. Used TinyUmbrella and kept 1.59 baseband, then used Greenpois0n. EVerything went fine.
I went to the loader and loaded cydia and everything was there.
Then, I saw the screen flash slightly and my wallpaper was changed back to what it was before I did the update and the loader and cydia apps were gone, along with the iPod and Email.
Used spotlight search and nothing comes up.
Double click the home button to bring up task switcher and swipe to the left and the iPod controls are there, but no iPod icon.
I then used Redsn0w to get the cydia icon and its running fine, but don't know where the launcher, ipod and email went