Hi Daniel,
Based on my experience in the Digital and Technology field I feel that a good extension of the project management certification into the Agile world is the SCRUM Master certification because it cast a different prospective on the delivery method. It is then up to the PM to deploy PM or SCRUM Master tools and techniques as he/she sees fits and, in fact realise the role of Agile Project Manager. I would be curious to explore the PGMP certification, I did the MSP a while back and I was not particularly impressed though, I don't remember learning as much as I learnt by taking the Prince 2 Practicioner or by studying for the PMP.
Carlo