There's so much waffle and sh*te written about management that you could easily get swamped. Before moving onto IT management specific books, I'd highly recommend "What Management Is" by Joan Magretta. First of all it gives a historical perspective of the evolution of managment over the last hundred years which is invaluable to give you the background to be able to put any "new" management theory into context. Next, it is the only material I've ever read about management (not much to be honest, it usually tries my patience no end) that avoids stating the obvious and concentrates on some of the surprising results in the field.
For IT management, "Rapid Development" by McConnell is the best book in my opinion but should be backed up by studying the classic works on software economics - like Boehm - etc.