Other first round HS players from the 2005 draft (he was in the same draft and round as Ryan Zimmerman):
Jason Upton - MLB since 2007
Cameron Maybin - AA with September callup 2007, MLB in 2008 & start of 2009, currently in AAA
Andrew McCutchen - AA 2006, AAA 2007, MLB 2009
Jay Bruce - AA & AAA in 2007, MLB since 2008
Brandon Snyder - AA & AAA in 2009
Christopher Volstad - AA 2007, MLB since 2008
Carl Henry - Released early in 2008
Mark Pawelek - A+ 2009
Colby Rasmus - AA 2007, AAA 2008, MLB 2009
Other than Henry, who was released during 2008 after 20 games in 2008, Thompson is pretty well behind all but Pawelek, who is is putting a patent on slow development.