Check out Hybrid Agile … what's that? by firstname.lastname@example.org. Here is an excerpt:
What’s the hybrid thing?
It’s agile coexisting in the same project with a traditional methodology, presumably for the swim lanes that are not software.
Some call hybrid agile as: agile in the waterfall
Are hybrids practical? After all, the traditional is top down planned, most requirements up…
The full article is available here.