Grants: how to acknowledge collaboration, techniques from postdocs or students?
Regarding "sometimes a postdoc has significant relevant experience that a PI lacks", I have been referred to by name in (successful) NSF proposals I have co-authored to highlight some expertise I bring to the project, e.g.


  ff524, a PhD student whose efforts have contributed to the research component of the project, will also be engaged in X. [insert my impressive background in X here]


or 


  This interdisciplinary collaboration is facilitated by ff524, a PhD student in Department A who has previously worked with PI X in Department A as well as with PI Y in Department B.


Presumably one could do the same with postdocs.