Alan Shalloway, co-author of Design Patterns Explained, blogs about the need for companies adopting agile techniques to look beyond agile project management and thereby consider the full development picture. His experience is that if agile project management is the primary focus, then developers will likely experience some difficulties during their transition to Agile. They have to come to understand that integration and user testing will be required after each iteration, and that the architecture of their system will evolve throughout the project. They must also learn to take a test-first approach to development, and work with smaller requirements "chunks" on a priority basis instead of a comprehensive requirements specification.
In short, Shalloway makes some very important and coherent points which you should take seriously during your migration to agile software development approaches.