CMMI or Agile: Why Not Embrace Both! is a new report that is worth reading.
on achieving a particular appraisal rating.
In contrast, implementing CMMI is using the model in the same way that engineers and architects use models: as a learning tool, a communication tool, and a means of organizing thoughts. The more implementation-oriented an organization is, the more improvement-centric it is; thus, the focus is on maturing and growing process capabilities rather than ratings.
CMMI and Agile can complement each other by creating synergies that benefit the organization using them. Agile methods provide software development how-to’s that are missing from CMMI best practices that work well—especially with small, co-located project teams. CMMI provides the systems engineering practices that help enable an Agile approach on large projects. CMMI also provides the process management and support practices that help deploy, sustain, and continuously improve the deployment of an Agile approach in any organization.