The shift to Agile has not changed the need for Agile Architecture but it has made its need more apparent. Architectures have always needed to change. In the Agile world, this is need is recognized up front. Here are some resources to help with emergent architecture.
Patterns are an effective thought process, not merely solutions to recurring problems in a context. This is a good primer on what design patterns really are and how their value goes well beyond “Solutions to recurring problems in a context.”
A question that often arises in our consulting and training practices concerns the relationship between Test-Driven Development (TDD) and Acceptance Test-Driven Development (ATDD) and, what we might call Unit Test-Driven Development (UTDD).
The reality is that they are all “Test-Driven Development.” They are not conducted in the same way nor are the done by the same people and the value they provide is different. But at the end of the day, TDD is the umbrella under which they fall. TDD is a software development paradigm. (Scott Bain)
A primer on emergent design (blog post)