Here's a Mock Draft in which the Astros are projected to take Stanford pitcher Mark Appel.
At this point Mark Appel looks like a clear cut #1 overall pick to go first overall in the 2012 MLB Draft. Appel is no stone cold lock to go #1 overall by any means necessary, but Appel has to be the frontrunner to be the first pick in the 2012 MLB Draft just like Stanford quarterback Andrew Luck is the frontrunner to be the first overall pick in the 2012 NFL Draft at this point in the draft process even though nothing has been finalized yet.
Click the link for summaries on Appel.