I am a little bit surprised by this move, but not terribly so. Catchers are valuable, and Heintz had another option year available, so I believed that the Twins would keep Heintz around for another year as insurance in case there was an injury (the same role he played this past season, in other words). However, the emergence of Jose Morales last season, and his addition to the 40-man roster late in the season, made Heintz expendable. Morales now slots into the third catcher role -- and honestly, he fits the position better. Heintz also was not really used by the Twins in the way a traditional catcher was, as over the last couple of years in Rochester he nearly played more in the infield than he did behind the plate. (Check out the comments for a further breakdown of this point -- although I will say that not seeing any stats as a DH, my original statement that he was in the infield or at DH more than he was a catcher may be correct. Unfortunately, I don't have the time to look that up right now, so I'll concede the point and go with this revised version).
The Twins might not be done making this kind of move -- outfielder Darnell McDonald and infielder Chris Basak both seem to be prime candidates for removal from the roster, since they are unlikely to contribute to the big league club. Also, the team should be adding a few players to the roster soon as protection against the Rule 5 Draft. As I mentioned earlier, I'll have more to say on that subject later today, when I discuss the players that I would add to the roster.