InfoWorld: offers a list. One of them:
2. Dismissing open source — or bowing before it
For better or worse, many IT shops are susceptible to religious behavior — a blind, unyielding devotion to a particular technology or platform. Nowhere is that more true than with open source.
On the one hand, the most conservative IT shops dismiss open source solutions as a matter of policy. Thats a big mistake: Taking an indefinite wait-and-see attitude toward open source means passing up proven, stable, and scalable low-cost solutions such as Linux, Apache, MySQL, and PHP. On the other hand, insisting on open source purity in your IT operation can delay progress, as developers are forced to cobble together inferior or unwieldy open source solutions when more appropriate commercial software solutions already exist.
Open source software is not inherently better than commercial software; it all depends on the problem to be solved and the maturity of the solution being considered.