Let me make it more clear:
The author of the wiki page will likely have his own criteria why he considers a post important.
For example in a forum "motorbike maintenance" there often appear reports about which sealant to use. So one user decides to write a wiki page "sealant how-to" - then he just wants to select the posts to show based on this aspect, not on community ranking.
There might be no "cool" interface for the wiki page editor in the first place, he might cope with a syntax like:
that inserts this post's text in a wiki page, or some kind of "macro".