According to a recent Forrester presentation, Lean is the way to promote BPM. One statistic that surprised me from that is that Agile, while the most common method for delivering BPM initiatives, still comprises only 34% of the approaches. Also surprising is that 20% still rely on Waterfall.
Forrester suggests all should use agile. I would say they should at least start with pilots, mockups and trial implementations on a limited scope and deliver value quickly. This seems obvious given the BPM tool set, yet many organizations still work with less flexible approaches.