Here's a summary of updates on the Twins' top prospects by BP's excellent prospect dude, Kevin Goldstein. The link is to part 1 and part 2 is here: http://baseballprospectus.com/article.php?articleid=10494. Both require subscriptions.
Hicks, #26: The Twins, being "notoriously cautious," are having Hicks repeat at low-A.
Sano, #35: Gulf-coast league action.
Revere, #46: Nice spring and has skills that should translate well in the majors. AA.
Ramos, #65: Had scouts "fawning" in spring training, and sets himself up as juicy, juicy trade bait for the Twins. AAA.
Gibson, #71: Also excellent reports this spring, demonstrating that he's deserving of a higher ranking. High-A.